ancient animal aquatic carapace Galapagos gicotea jicotea nature old reptile reptiles rough shell tortoise turtle algae background beach bivalve coast England Great Britain kent mollusc natural sea seashell seaweed shore texture abstract alone artwork ball brown bubbler crabs build burrow construction crab crab markings Crustacean design grain hidden hiding hole home imagination industrious marine ocean pattern play round sand sand balls Sand bubbler crabs sand bubblers sand marbles sandy shell fragments shells small sphere spheres spotted tiny tropical wildlife coral corals dwelling koraal polyps reef undersea white