My idea is simple, what if there were turtles in minecraft?
Size: 1.5 x 1.5 x 1
Drops: Turtle meat + turtle egg(lay eggs)
Spawn: Any body of water.
They will swim quite fast, however, when they get on to land, they will only walk 1/4 of the speed our minecraft human walk. They will lay eggs now and then, the eggs can be thrown with a chance to produce more turtles. When they die, the turtles will drop 1-2 turtle meat which will refill 1 hunger when raw and 3 hunger when cooked.
my 2nd idea is a giant turtle.
Drops: Turtle meat, giant turtle shell and giant turtle eggs.
It would spawn in a sort of underwater structure, since there are already structures in minecraft we can always have one more. The structures would spawn in ocean biomes and each ocean biome can only have 2-4 of this structures at a time, making them very rare. The structure will rise about 7 blocks from the seabed in a way that makes it look like a sort of underwater hill and should be about 15-20 x 15-20 blocks wide and 8 blocks deep under the seabed. There should be an entrance to the structure sort of like an overhang:
So that the water will not enter the structure and it would make the place harder to find. The structure should be coated in two layers, the outside should be dirt and the inner should be turtle stone. Turtle stone would look just like a stone but has green circles on it that glow despite light level, just like spiders eyes. This turtle stone cannot be picked up after destroying.
The giant turtle can only spawn on the turtle stones, making them bound to the structure and a rare mob. The giant turtle however can swim away if it finds the entrance. Just like normal turtles, the giant turtle can move quite fast on water and slow on land, maybe about 3 times faster than the normal turtle.
It would drop up to 2-5 turtle meat which is the same as what the normal turtle drops, and lays up to 3-7 giant turtle eggs which can be eaten raw for 1 hunger and 2.5 after cooking it.
Above I mentioned a turtle shell, it currently has no uses but I am thinking about turning it into the cauldron when placed instad of a metal block or using it as a hard to destroy boat.
The giant turtle was suggested by me as I wanted a resourceful yet rare mob that I can breed just like mooshroom.