Dugong is an unlockable friend in Abyssrium.
To obtain Dugong, you must have the Star Horn Coral, and have unlocked 78 types of friends. This is excluding premium friends, despite the fact that in-game, it says you must have "all types of friends."
Dugong is the only dugongid species alive, and one of the two that survived the Holocene along with Steller's sea cow, a cold-water relative that became extinct in 1768. Dugongs live in coastal waters of the Indo-Pacific. They're related and are very similar to manatees but unlike manatees, they're omnivorous and have peg-like molar teeth, to open crustaceans' shells, dugongs also have a whale-like tail in opposition to manatees' round tails. Like manatees, dugongs have a sharply downturned snout which they both use to graze benthic seagrass. They eat 70 pounds of seagrass daily.