Reminds me of....
This aquarium my son had about 10 years ago. The fish died and he kept the tank going because of these bottom feeder-like catfish that survived, even in the murkiest of water.
I salvaged those fish and put them in a new tank (and they lived for YEARS), however by the time I FORCED him to dump his tank and clean it out, it was full of these tiny black and white snails. He cleaned and rinsed it out in the front yard, and those snails could be found EVERYWHERE within 50 ft. for years to come. You'd find them on the house, wooden lawn furniture, the mailbox, even on the trees. The gift that keep on giving. Go forth and multiply! And they did.