Dog vomit slime mould (Fuligo septimia) growing at the foot of a dead tree. Morden, Surrey, England. Dog or dog’s vomit slime mould is believed to be harmless, though in at least one European country it is believed that witches used it to spoil their neighbour’s milk. It is a frequent cause of complaints from gardeners, who find it flourishing on their pine mulch. Nothing can be done to eradicate it, and turning a hosepipe on it will just help to spread the spores. Said to be edible, but not by me.