It is worth noting – as someone who’s reasonably knowledgeable about arguably the main example, king crabs – that carcinisation is really interesting, but I think some people took the meme semi-unironically as this especially widespread example of convergent evolution.

In reality, it’s in the true crabs’ sister infraorder, Anomura. Which is still super cool, but even the faintest notion that crabs are some singularly ideal male body body form is just a runaway shitpost.