Ranger Rachel spotted this Dog Vomit Slime Mold at Elvetham Heath.
In its growth stage this yellowish, foamy slime mold is an irregular mass that "creeps" gradually over wood mulch or other decaying material, engulfing and consuming bacteria, yeasts and fungi. It sometimes bleeds dark fluid and can look a little like dog vomit, hence its lovely name. In its spore producing stage it dries and hardens; becoming darker in colour, eventually becoming a mass of dark and dusty spores.
Creeping gradually across decaying wood, it can sometimes creep on to nearby living plants. These mysterious organisms are said to be the inspiration for the 1958 movie 'The Blob'! Stranger still, if you run water on to its spore producing stage, the water either rolls of it without moistening it or else a cloud of spores rise up like smoke, helping to spread it further.
Its not poisonous but I doubt it makes pleasant eating, although reportedly it is eaten in Mexico!
This is one of many strange but important organisms that have a crucial role in ecosystems, feasting on decaying organic materials and the microbes that inhabit them. They have an incredibly important role in breaking down the tough materials living things are made of and returning those nutrients to the soil.