Back in July this one log at the dog park produced an extraordinary display of this amazing slime mold! The next 4 photos show various stages of it.

Slime molds are odd things, once classified as fungi, now in the Protist group described as: "a eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus." (Wikipedia), and divided into three main groups. They feed on fungi and bacteria. Some forms of slime molds can move, oozing along slowly, as this one is doing. They are complex and fascinating and there is too much to say about them in a limited space.