Your arm is homologous to a bat's wing.

Tardigrades / water bears are microscopic animals, probably a sister group to arthropods (insects, crustaceans etc.) and velvet worms.

Now here's a fact that will mess you up for the rest of the day.

An entire tardigrade is homologous to an arthropod head and the tip of its butt. Tardigrades have gotten rid of the entire thorax and abdomen.

Imagine just your head and your butt walking around on your beard.

#biology #zoology