This is a slime mold (commonly called dog vomit fungus). It's fairly common to see these occassionally on wood mulches. The fungus "feeds" on bacteria in the mulch and it's just temporary. It's not toxic or dangerous to humans, animals, or plants. It will evenually disappear, or you could scoop it up and put it in the trash.

This page and the attached fact sheet provide additional information:

Slime Mold - Ohio State

Christa

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