1st Update (2/18/21): Added more details to section 2.1 and a new section on crystalline protodermis.
2nd Update (2/27/21): Added more details to section 2.1 and 3.2, as well as a new section on organic protodermis.
Introduction
Protodermis is a synthetic atomic element.[1][2] It is also very versatile,[3] similar (but not identical) to carbon.[4] It is able to form molecules,[5] but it is unclear whether the molecules used in the Matoran Universe are actually compounds (consisting of multiple elements). It is not nanotechnology.[6][7] Protodermis, being an element not discovered or synthesized in real life, must have an atomic number higher than 118. Beyond this, we do not have enough information in canon to make general statements on protodermis, but we can further investigate specific forms of it. Because energized protodermis is not required at all in the creation of protodermis[8][9] and the Great Beings created protodermis before even discovering it,[10] it will be considered a distinct substance and not included in this analysis. What will also be left out is the creation process of protodermis and how antidermis is a byproduct of it.
1: Metallic Protodermis
Toa of Magnetism can affect all forms of metallic protodermis, but cannot magnetize substances that were not already magnetic.[11][12] This means metallic protodermis is ferromagnetic. It can be affected by magnetic fields[13] and even be turned into permanent magnets but is not naturally so.[14][15] This is also how Gahlok-Kal was able to magnetize (the metallic parts of) several Mahi to Pohatu Nuva (Bohrok-Kal Online Animations).
Metallic protodermis can also rust, including Protosteel,[16] but the only known instance of natural rust is the Vahi from being in the Silver Sea.(“Chapter 1.” Time Trap, p. 10) Because metallic protodermis and liquid protodermis are simply different states of the same molecule (see section 2), the likely source of the oxidation is from the rock-like protodermis sediment in the raw liquid protodermis (see section 2.1).
1.1: Protosteel
Protosteel is the toughest variety of metallic protodermis, but what is important is that it can conduct electricity.[17] It probably is not an alloy, but rather a differently crafted form of metallic protodermis, along with other ‘precious metals,’[18] transparent masks,[19] and copper masks of victory.[20][21] Since the strength of the metal depends on how well it was forged,[22] this would explain why protosteel is hard to work with[23] and only Artakha and Nynrah Ghosts, both exceptional at crafting, can do so.[24] If the difference in quality for metallic protodermis is simply in how it was crafted, which most likely was not a chemical process but a physical one, then it can be assumed that the conductive property of protosteel is shared by all other forms of metallic protodermis since they are the same chemically. What all this implies is that metallic protodermis molecules have free electrons.
2: Liquid Protodermis
Pure liquid protodermis was magnetized to be used in chutes on Metru Nui (Metru Nui - City of Legends, p. 61). This means it is also a ferromagnetic metal, implying that it is the liquid form of metallic protodermis, evident from the fact that molten protodermis, which is liquid protodermis that has been heated,[25] could be returned to the Silver Sea (Metru Nui - City of Legends, p. 8).
At first, this would seem universe breaking, as Toa of Magnetism/Iron should be able to control it as well, thus rendering Toa of Water useless, but this is not true. Toa of Water are capable of creating and controlling not just liquid protodermis, but also actual water,[26] as well as using their power to heal.[27] While Toa of Magnetism could theoretically control liquid or molten protodermis, they cannot create it,[28] and Toa of Iron cannot control it in the same way Toa of Ice cannot control water,[29][30] even though water and ice are both the exact same compound.
The only way liquid and molten protodermis can both exist is if metallic protodermis’ boiling point is high enough where molten protodermis does not evaporate. Gaseous protodermis does exist,[31] as it is the clouds above Metru Nui.[32] This means metallic protodermis has a ‘water’ cycle.
2.1: Liquid Protodermis Purification
The purification process of liquid protodermis involved rapid heating and cooling (Metru Nui - City of Legends, p. 8) and a separation tank (Toa Nokama CD-ROM), but what exactly it was separating is not given. The impurities of liquid protodermis were the same as any other substance.[33] To compare to liquid protodermis, the impurities found in actual water are suspended solids, mostly from sediment. It seems likely that the raw liquid protodermis contained sediment of solid rock-like protodermis and metallic protodermis, which is not purified.[34] The Silver Sea is confirmed to have some sort of sediment in the form of “mud and silt” (“Chapter 1.” Time Trap, p. 9). The 2004 Story Bible states that “the Ga-Matoran cleanse marine sediments containing protodermis.” This also explains why raw liquid protodermis had a metallic coloration, which it lost and became bluish or clear after being purified (“Protodermis Purification.” Encyclopedia Updated, p. 116). The separation tank would remove the rock-like protodermis, while heating the liquid protodermis to become molten would cause the solid metallic protodermis in the liquid to also become molten, so that when it was cooled, the liquid protodermis would be homogeneous. The rapid cooling of the molten protodermis was very likely supercooling, which can cool the liquid below it’s ‘freezing’ point without it becoming solid. Despite the name, the temperature to supercool liquid protodermis was likely not that low, as metallic protodermis exists as a solid at room temperature.
3: Crystalline Protodermis
There are two main forms of crystalline protodermis: frozen and crystal.[35] This does not include protodermis cages, as those are more like rock-like solid protodermis than crystalline.[36]
3.1: Frozen Protodermis
Frozen protodermis is liquid protodermis that has been frozen[37] and is not stronger than regular ice.[38] If what has already been concluded is true, that metallic protodermis is the solid state of liquid protodermis, frozen and metallic protodermis should be identical, but this is not the case. What makes a substance ‘crystalline’ is the arrangement of its atoms being in a crystal lattice structure. This implies that metallic protodermis is non-crystalline, also called amorphous.
3.2: Crystal Protodermis
The most notable instance of crystal protodermis is that created by The Shadowed One’s staff. However, it is likely that lightstones and heatstones, which are related to lightstones ( “Heatstone.” Encyclopedia Updated, p. 43.), are also this form of protodermis.[39] The difference would be that TSO’s crystals do not give off light or heat.
While frozen and crystal protodermis are different, crystal protodermis does seem to still have a connection to liquid protodermis. Lightstones can be refined, which not only dims them (“Lightstone.” Encyclopedia Updated, p. 79), but also turns their color from yellow to bluish-white.[40] It is unknown if the refining process is similar to the liquid protodermis purification process, but it is probably no coincidence that both turn protodermis the same color. According to BS01, Knowledge Towers are also grown from cradles of pure liquid protodermis.
4: Organic Protodermis
Organic protodermis is by far the most difficult form of protodermis to understand due to its complexity. There have also been some contradictions surrounding it. Greg has offered different answers on whether organic protodermis has a cellular structure.[41][42] However, microorganisms possibly exist, which would imply cells.[43] Organic protodermis does not have DNA or a genetic equivalent,[44][45][46][47][48][49] despite Greg stating otherwise later on.[50][51]
Conclusion
This analysis is not meant to be exhaustive, as there are still many unanswered questions about protodermis, and they may never be answered. What this analysis does is provide an introductory theory for at least certain aspects of protodermis.