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, amongst others. It is used for copulation and varies in size and shape by species. Its characteristics are sometimes used to differentiate between similar species. The oosik of Native Alaskan cultures is a polished and sometimes carved baculum of various large northern carnivores such as walruses. The raccoon baculum is sometimes… (More on Baculum)