Many of the comments being “penis worms!”, but no one is asking about that Red blood is only in the “majority of vertebrates” leaves me wondering which vertebrates have what other colour(s) of blood.
Edit: I have been told that it’s “Crocodile Icefish” (10 species of) and colourless.
Thanks, @Marcos@discuss.technics.de
Thanks for the callout and link! 🙏🏽
Nature is fascinating.