Organisms use phosphorus to help maintain homeostasis Phosphorus is a building block of molecules that function in making organisms.

but there is no

i guess you forgot putting it.

synapse nervous system

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.