Scientists in Australia have uncovered the mystery behind the bizarre four-headed echidna penis by creating an advanced 3D model of the peculiar organ.
There are four species of echidnas that, along with platypuses, make up a unique group known as monotremes — the smallest of the three mammal groups — whose members lay eggs like birds and fish, but also produce milk like other mammals. Much about this group remains a mystery, the study researchers said.
One of the biggest monotreme mysteries is the echidna penis, which has four separate heads, or glans, at the end of the shaft. If that wasn’t weird enough, only two of the heads are used during each erection, and echidnas can alternate between which two they use.