The sea-hare is found in some medieval encyclopedias. Its head is similar to that of a hare. It is extremely poisonous, so that merely touching it causes vomitting. The sea-hare of Western ocean is like a hare in color only, but in the Indian sea it is like a hare in size and fur.

There is a group of marine molluscs called sea-hares. They can be quite large, and have a rounded body with two long projections from their heads that resemble the ears of a hare. The animal has been known and described since Roman antiquity or earlier.