Slime mould, often called Dog's vomit slime mould (Fuligo septica), not a fungus but an amoeba-like organism that engulfs bacteria and other prey with its pseudopods. Australia.

Many people are coming in to Possum’s with pictures of a black film over the leaf blades of grass. What you see is the fruiting body of a fungus that is decomposing thatch and other organic ...