Mold

Mold has a rare chance of growing in deep caves that may have water nearby, And can grow in abandoned places, example abandoned village. It can also be green mold growing on crops that were left out longer then 10 Minecraft days. Both can harm you. If you are exposed to the black mold long enough you will get poison effect, and maybe even die, Green mold can harm you by giving you a longer poison effect, which can happen if you eat it, It can be broken with a shovel. Black mold can be removed with water.