I came across two odd things last week in Gilmore Ponds, a Butler County MetroPark in southwest Ohio. The first was hearing a sickening "crunch" when I unwittingly stepped on the body of a dead crayfish; specifically the front half of the body (cephalothorax = head + thorax) since the abdomen was missing.
The second odd thing was a foul odor hanging in the air which I thought was wafting from a dead animal. I was correct, but the stench was drifting from dead animals, plural. I came across hundreds of dead crayfish in various stages of malodorous decomposition. Almost all of the bodies lacked abdomens indicating there were probably some satiated raccoons, possums, etc., and birds of all sorts, near at hand. Of course, the question at hand was "what killed all of the crayfish in the first place?"