Echindas are to sesamoids as some other unusual thing is to something like itself
Okay, I fell a little short on the analogy. But my point is that the Echidna from the last post is in some ways less random than it first appeared. Because Echidnas are monotremes, and there are only three kinds of these egg laying mammals. And sesamoid bones are the bones that don’t connect to other bones, but are just held in place with tendons. And there are only a few of them. Well, maybe twelve. Out of 207 bones in the body.
So not as rare as Monotremes.
So not a very good analogy.
Whatever. It’s a good excuse to post another echidna picture.