New shrubby mountain biome.

This would add small shrubs and bushes on top of certain mountains. These shrubs would mostly be decorative and would add some colour to mountains. A new rodent mod could spawn in these mountains and have the ability to hide in the shrubs like silver fish, and pop out when you step on the shrub it's hiding in. Some of the bushes would be solid and some can be walked through (these are the ones the rodent mod would hide in).