This is my proposal for a new mob to add to the nether. It will involve an AI change to the nether-hound to complete the effect. I realize this is no small task and do not expect it to be added any time "soon."--------------------------------------Description (off the cuff) The nether-sheep stalks the burning wastes, silently, feeding on mushrooms and netherwart, while avoiding nether-hounds. It can be sheered, for a minute or so after growing a new coat. But you better hurry. Its coat changes every few seconds from white, to light gray, gray, dark gray, then black. Not long after it turns black the nether-sheep bursts into flames until the wool is consumed, injuring all who come near. Yet the burning wool leaves the nether-sheep naked and unscathed after the couple of minutes of burn time have elapsed... The closer they are to open flames the faster the coat changes color and ultimately lights up.The flames can be doused with a cauldron of water, evaporating the water and leaving them clad in black wool, resetting the timer to burst into flames. (A non-burning sheep does not consume the water in the cauldron). However, if you've never tried coaxing a sheep into a cauldron, let's say for a special recipe in the overworld, it's no trivial matter. Sheep have minds of their own! Leads cannot be used. They burst into flames, being utterly destroyed, delivering a full heart of damage to the one attempting it, even if the sheep is not yet aflame!As the descendants of domestic sheep brought to the nether, nether-sheep are friendly and even seek player companionship. This and their propensity to burst into flames makes them quite dangerous to the ill prepared. They appear in flocks of 2 to 4. And, until they ignite, are almost indistinguishable from regular sheep. (The ever darkening wool should be a clue)Unlike their overworld counterparts, nether-sheep can't be bred by using wheat. They must be fed nether-wart instead. As well, dyes do not affect nether-sheep. Any attempt at dyeing them is wasted consuming the dye to no effect.Nether-hounds are their nemeses. Absent a player to harass, hounds will turn their attention to the next tastiest meal they can think of, nether-sheep. So, if you somehow manage to survive wrangling, raising and sheering these animals, keeping them alive will be your next big challenge.Since leads cannot be used on them: to date nobody knows if nether-sheep can even make the journey back to the overworld. For all we know, any that make the journey revert to normal sheep, or just die in the process.