Hydrus (legendary creature)

The Hydrus (also known as Enhydros, Enidros, Hildris, Hydra, Idra, Idres, Ydre, Ydris, and Ydrus) is a creature from Medieval bestiaries.

While in the Nile, a crocodile would roll the hydrus in the mud before eating the smaller creature.

Another interpretation is that the hydrus would intentionally roll in the mud and seek out the crocodile while it slept with its mouth open.

Normally it is considered to be a water snake, although Pliny the Elder believed that it was an otter.

Other animals the hydrus has been thought of as include a bird, a dragon, and a mongoose.