Guardian

The Unknown Hostile Underwater Mob is a mob that Jeb is working on. It will be hostile and will only spawn underwater. Nothing else is known about it other than the fact it will not be a shark or a barracuda.

The new hostile mob will spawn in Water Dungeons containing Prismarine and Sea Lantern.

It will be a rather "nasty" mob. Its health, attack strength, drops, model and name are all unknown.