Slime molds are not true fungi but, instead, fungus-like organisms that exist in nature as plasmodia. Slime molds grow on, engulf, and absorb their food which consists of decaying organic matter (particularly in the thatch layer), bacteria, and fungi such as those found in soil and organic mulches (especially hardwood mulches).
Slime molds are highly sensitive to their environment and typically disappear in dry conditions. Though unsightly, slime molds are not known to be dangerous to humans or animals, cause little to no damage in the landscape, and assist in natural decay processes.
See Clemson’s Home and Garden Information Center’s (HGIC) for more information on HGIC 2354, Spanish Moss, Lichens & Slime Molds.