Our saltwater aquarium at work died.
Last summer, a former employee was moving with his family to Florida, and his brother who had said he'd take the tank backed out at the last minute, so my boss agreed to let him set it up in the lobby. It had two clown fish, on royal gramma (bright yellow one end, bright purple the other), and a bunch of rocks with live soft corals on them. It quickly started growing an icky red algae and had various other problems. We have a place just down the street that specializes in salt water, corals especially, and we wound up paying them to come in and get everything in order. (Apparently the former owner was doing almost everything wrong, which does not really surprise me....)
The fish were colorful, snails and crabs provided even more critter entertainment, and I was surprised how interesting the corals could be. One, especially, which I'd saved from falling off its rock by putting its base into a little hole on another rock, had turned out to have at least half a dozen different shapes it could take on, and I could occasionally see a tendril/frond/whatever fold in around some tasty bit of debris, and I watched it grow and thrive. We'd recently added two peppermint shrimp to get rid of some less desirable growths, and they'd just started coming out of hiding more and doing their job. The tank was looking really good!
Well, this morning when I came in the lights were off, but once the lights came on in the tank, first time I walked towards it I could see all the soft corals were drooping down over their rocks instead if standing up, and when I looked closer, the fish were floating at the bottom, not moving. Even the little peppermint shrimp were lying dead. The water felt noticably too warm, and when I floated the thermometer it was almost 100°F. Apparently, the heater malfunctioned, and stayed on instead of switching off when it got too warm. Our poor little fish and shrimp and crabs and snails, and all those live corals, got cooked and died in one night.