You've probably seen blue crayfish, but have you seen blue lobsters? I took these pictures at the aquarium where I work, Maritime Gloucester's Sea Pocket Lab in Gloucester, MA. These are mutant American lobsters (Homarus americanus). Their genetics caused unusual coloration. All are highly rare. The green was may be an albino, and if so, it's an estimated 1 in 100 million. I'm not sure about the partially blue one, but it may as rare as 1 in 50 million. Fully blue lobsters, ranging from dark to light blue, are an estimated 1 in 2 million. All were donated by local lobstermen and lobster companies.