Once you’ve seen a slime mold—its gooey, delicately branching structure oozing in a vaguely unsettling way along a log or leaf—you’re unlikely to forget it. They’re unmistakable because there’s ...

Anyone who has hiked in the Northwest has seen a slime mold, but likely didn’t know it. Some appear like tiny balls of fungus on rotting logs, or strange patches of gooey orange globs. Some look like ...