AKA "square grouper"
WARNING: Thread drift...
Walked into the Carribean Club in Key Largo after work one evening back in the early 80's. Sat down at the bar with some co-workers and started drinking when someone says, "Hey, check that out." Across from the place was a small strip of beach. Sitting half out of the water was a distinctive-cube shaped object. We all pondered it for a while until it got dark enough and we got drunk enough to forget.
The owner told us the next evening that sometime soon after closing, a van pulled up in the side parking lot and two guys jumped out, ran over and grabbed the bail, loaded it into the van and split the scene.
Pretty common jetsom in the Keys about that time.