Final answer:
A mushroom growing around a tree trunk is an example of a fungus.
Step-by-step explanation:
A mushroom growing around a tree trunk is an example of a fungus. Fungi are multicellular organisms that consist of two distinct morphological stages: vegetative and reproductive. The vegetative stage is characterized by a tangle of slender thread-like structures called hyphae, while the reproductive stage is more conspicuous and can form fruiting bodies, such as mushrooms.