Dear Ken, the most common slime moulds on lawns are Physarum cinereum, Mucilago crustaceum and Fuligo septica. Fuligo septica has the most unfortunate common name of Dogs vomit fungus.
As you may have found out slime moulds share similarities between a fungus and single celled animals. Although unsightly they do not kill plants at all. They simply obtain there food by obtaining bacteria.
Some moulds live as single cell structures and others become large plasmodium like structures.
Of course they give off millions of spores and some can survive many winters before germinating. Unfortunately there is no control as it is mostly caused by environmental issues!
Some people do say wash it off with a hose if it becomes unsightly. This I believe spreads it, and I have done a lot of greenkeeping in my career. The thing is it appears and then disappears. Best thing to do is keep off it, although it spreads spores anyway!
Regards from England.
Neil.
