Walrus

Walruses were Earth marine mammals. They were among the animals kept in the sea room of Shaun Brett's monument to his deceased father. When the Permians revived, they inadvertently used their bioelectric fields to fuse the walruses' bodies with those of the other animals to form monstrous hybrids. (BFA: The Land of the Dead)

On Hyspero, the Scarlet Empress sent a giant walrus to attack the Eighth Doctor's expedition. (EDA: The Scarlet Empress)

Nimbit was a member of a species which resembled walruses. (EDA: The Tomorrow Windows)