The baculum (also penis bone, penile bone or
os penis) is a bone found in the penis of most mammals. It is absent in humans, equids, marsupials, lagomorphs, and hyenas, among others. It is used for copulation and varies in size and shape by species. Which is why it's an irony to call 'it' a boner this is a racoon penis bone. And a certain extinct species of walrus has a ...