I have no special education or expertise, just Google, but your description those sound like some variety of inky cap mushrooms. Some of them are used for food, but some can be hazardous (and one of them is fine unless you drink alcohol, in which case it can cause a literally lethal hangover).

I had a bunch of them turn up in my compost heap, and there they were an indicator that things were a bit too wet (but worms like slightly wetter conditions anyway, so that may not be a bad thing in vermicomposting). They up and died on their own when things dried up a bit.

A quick search for inky cap and vermicompost turned up a thread on these forums where someone was using them as worm food successfully. I'd just leave them be, keep an eye on the worm bin, and if there are no other problems, just call them free help breaking down harder fare into something the worms can eat.

My view is it's perfectly fine in a bin or a compost pile, pretty much whatever kind of mushroom it is, and it does sound like some kind of inky caps. They're often associated with dead wood, which in a vermi or other compost just means they're breaking down lignin and/or cellulose (e.g. in cardboard or other bedding). And in the process they'll provide food for other organisms in the compost.

Also, unlike isopods to help break down tough woody stuff, inky caps are very unlikely to munch on tender young seedlings if you use your vermicompost for plants that haven't gotten bigger and stronger yet.

I think it would be a mistake to try to keep a bin that's purely worms, organic trash, and worm poop; you have a whole small scale ecosystem there. I look at a variety of life forms in the worm bin as a sign of a robust system. Worms don't like the meaty grease on an old pizza napkin? I'm sure the mites or the odd roach or maggot will be along to clean that up. Twiggy stems on old leaf bedding taking a long time to break down? Guess the worms can eat on fungus and isopod poop after they pre-process it, they handle it fine. Pest bug hitched a ride and is trying to cause trouble? Good thing the night watch spiders are there for security.

Maybe it has something to do with the Full Lunar Eclipse (of early this morning) and the (supposedly) 'Blood Red Moon'.

"And in the End of Days there will be signs and wonders and great happenings. There will be Trials and Tribulations and black mushrooms will mysteriously appear in worm bins everywhere. Sinner, Repent! The end is Nigh" (or something like that).

Shaul

Wow Shaul, and I just thought they were just mushrooms. Who new I could be missing the obvious. :) lol