Quest Ram

The Quest Ram is a very rare and special mob that spawns in a Quest Grove. It appears as a large ram with glowing stripes on its body. They are very valuable as when they are fed one of each of the 16 colors of Wool, they will return to the player one block each of Iron, Gold, Emerald, Lapis Lazuli and Diamond as well as a unique item: the Crumble Horn. They spawn only in Quest Groves, which are found only in the Enchanted Forest, which is very rare in itself. Even then, Quest Groves only have a chance of spawning. If you find a Quest Grove but no Quest Ram, wait patiently in the Quest Grove, and one will spawn.

Wool can then be fed either by right-clicking the Quest Ram with wool in hand or by dropping the wool in front of the Quest Ram, in which the Quest Ram will subsequently "eat" the wool entity. The Quest Grove also contains a Dispenser with wool of various colors that can be used if the player does not have the sufficient quantity of wool.

Each time a piece of wool is fed to the Quest Ram, potion particles with the wool color will surround the Quest Ram for a second or two. Wool colors can be fed in quick succession without waiting for the potion particles to subside. In addition, the Quest Ram will gain a new stripe on its coat corresponding to the color of wool that has just been fed. This stripe will also elongate the Quest Ram's mesh by one pixel per stripe, causing a completed Quest Ram to be much longer than an uncompleted one.

Once the Quest Ram's "quest" has been completed (the Quest Ram has received one of each color of wool and all the stripes have been acquired on his coat), it will reward the player with the aforementioned rewards. The Quest Ram will retain his stripes and the memory of the Quest's completion and not die, so the quest cannot be completed again with the same Quest Ram. Thus, infinite generation of vanilla materials is impossible.

Adapted from the [Forest Wiki]