Although they look like plants, lichens are comprised of algae and fungi living in a tight, symbiotic relationship. Lichens can be crustose (crust-like), foliose (leaf-like), or fruticose (shrub-like).
Fungi that live underground or within logs and other decaying substances produce above-ground fruiting bodies; some of which are naturally poisonous. Others, such as truffles, morels and some mushrooms are safe to eat.