General Attributes
Sea-pigs dig up the ground under water like pigs do on land. They must submerge their snout in the sand in order to gather food.
Sources
Isidore of Seville [7th century CE] (Etymologies, Book 12, 6:12): Sea pigs (porci marini) dig up the ground underwater like pigs; they must submerge their snout in the sand to gather food.