Next time my Pennsylvania crayfish is out I will take a pic. It has dug a hole in the gravel under a plastic house. As they are COOL to watch in the tank. They are a living bulldozer... Alway moving everthing around. I got mine out of a creek next to my home for free. I believe it's a female. And it has never bothered my fish ... So far... Also it seems to be tolerant to the high ammonia levels in my tank because the tank is still in cycle. As I did not know about the ammonia cycle before I started my tank.
THANX