The most amazing organisms are sometimes right in front of you and you don't notice them. This slime mold, Fuligo septica, a myxomycete, a kind of fungus, showed up on a lot of recently put down bark mulch.
It rained a lot and then these big patched of white leathery slippery stuff started accumulating, and the colonies were up to 20 cm in diameter (that is 8 inches for you non-metric readers:).
After a few days the white turns into brown and small black dusty things show up on the top surface and then it kind of dissolves and composts itself back into the mulch.
And the name is perfect. Dog vomit slime mold - that is the accepted, correct name, and it sure looks like it. Sometimes this species can be yellow instead of white, especially if there is a lot of heavy metals in the soil.