Yabbies and marron are Australian freshwater crayfish — hard-shelled, claw-bearing cousins of the lobster that live in the continent's dams, rivers and billabongs. The prize is the sweet, firm, faintly nutty tail meat, cleaner and less briny than a saltwater crustacean, that turns from mottled olive-green or slaty blue to bright orange-red the moment it hits boiling water. The yabby is the small, hardy everyman's catch of the eastern states; the marron is the large, prized Western Australian delicacy.