Fungi are referred to as heterotrophs because they cannot make their own food like plants do. They do not have chlorophyll, which is the pigment that allows plants to produce their own food through photosynthesis. Instead, fungi obtain their nutrients by absorbing them from other organisms, dead or alive. This process is known as heterotrophy. The fungal body, known as mycelium, consists of a network of filaments that helps them to break down and absorb nutrients from their surroundings. Fungi do not have roots, but they may have structures called rhizoids that function similarly to roots.