For the record, my unwelcome-but-interesting visitor is probably a "Dog's Vomit slime mould," arguably the least pretty of the species. Many slime moulds have ornate fruiting bodies or spore producers, but this beastie settles down, turns solid, and converts its internal structure into a blood-red mass of spores.

This is the second one of these critters I've had. I don't think they're particularly harmful, they mostly eat mulch, but they're unattractive and I'm not too sure I want my mint covered with slime mold goo.

Still, they're interesting creatures. I'm a bit of a fan of them, after watching a documentary on slime molds some 10 years ago (I was in high school, I think, so more like 15 years ago now, sigh).

Since this beast is more or less unkillable, I'm sure he'll re-appear somewhere else the next time I garden...I'd been joking occasionally about wanting a pet slime mould, but not this particular species, it's unusually disgusting :)