The Darwin Mod is an interesting mod that allows you to create weird mobs. There can be Pig-Cows, Chicken-Zombies and even Spider-Squids.
This simple list included in the post shows how diverse the mobs can be...
- a body (4 possible shapes)
- a head (3 possible shapes or none)
- a snout (3 possible shapes or none)
- ears/horns (3 possible shapes or none)
- a tail (3 possible shapes or none)
- 2 rear legs (3 possible shapes or none)
- 2 front legs/arms (3 possible shapes or none)
- the speed it can move depends on the size of the legs
- rotation of the body (from 0 to 90°)
- color (16'581'375 colors)
- skin (11 different skins)
- dropped item (126 possibilities)
- AI and behaviour: depending on some genes, some tasks are added like "hunt cows" for example or "flee when hit" or "look for shade".
- other behaviours: burn in sun, hurt by water, immune to fire...
- ―The mod's creator
When mobs are bred, a larvel state of its child is born. The larvae looks simply like it's adult state's torso.
This is a pretty cool mod, it was made the (possible) geneticist Manchou and can be found here.