Fungi thrive in the damp conditions found underground and play an important part in recycling nutrients by decomposing organic material. Like the heterotrophic bacteria they obtain ready made organic molecules from the tissues of other plants and animals. These food sources are usually dead or decaying but there are some fungi that attack living tissues. The lack of light underground appears to affect the ability of some fungi to produce fruiting bodies (the familiar 'toadstools') and for others to grow into shapes not normally seen on the surface, this can make identification difficult. Most of the larger fungi live on dead and decaying wood. In a cave like Porth yr Ogof there is a never ending supply of this dead wood and associated fungi brought in with the floods.