Old, detached, dead parts of a tree or collapsed tree trunks are called Deadwood. Even though it is anything else than dead. A lot of species live on and from deadwood, like woodlice, centipedes, millipedes, larvae of many species of beetles, fungi, bacteria, moss and lichen. Deadwood is important because after many years it decomposes and becomes valuable soil and part of the forest floor. Deadwood is also a necessary habitat for many species of beetles.