This little fungus belongs to the 'ink cap' group of genera (Coprinus, Coprinellus, Coprinopsis and Parasola). These are saprotrophic fungi, that is they decompose their substrate releasing nutrients back into the environment. You are right they don't last long. With some species you will see the pileus (cap) liquifying (auto-digesting) from the outside margin towards the centre as they spores mature. Resulting in a black slime!! They are black spored. Sorry I can't be any more specific than that from a photo.