Crawfish, crawdad, crayfish or freshwater lobster is shedding his exoskeleton. It must feel good to get rid of the old crust and get new armor. The change takes just a few minutes and meanwhile, the tiny creature is totally vulnerable to predators. Although I am not certain, I believe that this might be the species Cambarus (Hiaticambarus) longirostris Faxon 1885.
In a small stream in Macon County, North Carolina, USA