abstract alone animal artwork background ball beach brown bubbler crabs build burrow coast construction crab crab markings Crustacean design grain hidden hiding hole home imagination industrious marine nature ocean pattern play round sand sand balls Sand bubbler crabs sand bubblers sand marbles sandy sea shell shell fragments shells small sphere spheres spotted texture tiny tropical wildlife active animals aquatic closeup crustaceans decapod exoskeleton gregarious India macro nocturnal crabs pincers sand-bubblers Scopimera art branch branching bubble crab crustacea details dotilla dotillidae environment feed food foraging intelligence life little marble marbles memory network process art radial shore structure symmetry bubble Camouflage critter hide