Can Inter-species Fusions be Natural?

A couple of friends and I were chatting about fusions and it occurred to us that no one knew the answer. This is considering any combination of species - for example, if a Makuta were to try to fuse with a Toa, would they need a Mask of Fusion for that to happen, or could they simply merge their wills? (I know the Makuta are pretty touchy about their individuality, but of course this is a hypothetical.)


In 2005, Greg said that he was “inclined to believe” that fusions cannot be formed with different species:

There are multiple later quotes saying that kaita cannot be formed between different species:

However, he also confirmed that a Toa and a Matoran could form a non-kaita fusion: