Mycelium is the vegetative part of a fungus, consisting of a mass of branching, interconnected hyphae. It's the precursor to the fruiting body, or mushroom, that we typically associate with fungi. Mycelium grows by breaking down organic matter and absorbing nutrients, creating an intricate network of fine, white tendrils. This network, often referred to as the "wood wide web," allows fungi to communicate, share resources, and even manipulate their surroundings.