New mob - Seal

Seals could spawn naturally in the following biomes:

Frozen Ocean

Frozen River

Deep Frozen Ocean

When killed, a Seal could drop a random fish type as a food source.

This new mob would be an enjoyable addition to the frozen oceans, and its spawn rate would be the same as or similar to that of the Polar Bear

The Seal could sometimes come out of the water to sit on an ice block in the Ice Spikes or near the Frozen River biome.

The main purpose is to make the aforementioned biomes a little more alive.