Crayfishes, despite what their name suggests, are not fishes, but freshwater crustaceans resembling small lobsters. They are quite common in the creeks that run thru the woods near my house. Occasionally, I encounter their chimneys, the openings of their burrows.
According to the literature1, 2, some species of crayfishes spend most of their lives in burrows, while others burrow for various reasons, for example to escape desiccation during times of drought or to move below the frost line during winter.
Different types of crayfish burrows (from Pennak). X marks the place where the crayfish was found.
I don't know what type of a crayfish had made this chimney that I photographed last September. It was on muddy ground near an inlet of Little Seneca Lake that had become too shallow for a crayfish to live comfortably. Perhaps, in this case, the crayfish was hiding in the burrow underneath this chimney waiting for the water level to rise.
1Pennak. Fresh-Water Invertebrates of the U.S., 3rd ed., 1989.
2Hobbs (Chapter 22) in Ecology and Classification of North American Freshwater Invertebrates (Thorp & Covich, eds), 1991.