So we know that the concept of death, murder, and war exist in the MU, so what exactly happens when a being physically dies? I know their spirit is sent to the Red Star, but do Matoran bury their dead? Do they recycle their parts Boxor/Ussanui-style?
Dead Matoran are teleported to the Red Star so their data can be downloaded, so there isn’t a body to bury. I’m not sure if their masks are left behind or not. Takanuva still had Jaller’s Hau in MoL, but it’s possible it was removed before the body was teleported away.
They just go to the red star and back
This, provided their brain remained undamaged, since it was required for said download. They do have a habit of honoring beings with statues and the shapes of tribute masks, however.
Kanohi would probably only be taken if still intact and attached. Especially once you factor in that Jaller’s mask also formerly belonged to Lhikan.
Or they would have, anyway, had it not malfunctioned.