Sclerotium is a ball of mycelium produced by certain species of mushrooms. The sclerotium stores food that the fungus can use to reproduce. When the sclerotium of a mushroom is mature, it detaches from the fungus and lays dormant. Sclerotium allows fungi to survive when growing conditions are unfavorable.
Sclerotium is composed of mycelium and nutrients for the fungus. Mycelium is the fungal equivalent to roots. Mycelium spreads out in the soil or growing medium that the fungus is living in.
So a sclerotium can fall to the ground and begin growing a new colony of fungi using its nutrient stores and mycelium.
The part of the mushroom we typically think of is the stem and the cap that grows above the ground. The part of the mushroom above ground is also referred to as the fruiting body.
Sometimes, sclerotia mature and fall to the ground in order to ensure survival of the fungus during times of natural disasters or drought. Other times, sclerotia detach in the winter time and complete their life cycle in the Spring.
The sclerotium of certain psychoactive fungi are sometimes referred to as magic truffles or Philosopher’s Stones.