The Nautilus shouldn't spawn in cold biomes and shoud be a deep ocean mob

I believe the nautilus's spawning behavior is unrealistic; it is far too easy to find and poses no real challenge to obtain. Just like in real life, the mob should only spawn in warm biomes and deep waters, rising to the surface only at night. The zombie nautilus, on the other hand, wouldn't have this limitation, since it is already dead and doesn't have those needs.