At the top are some lettered olives (Oliva sayana), about 5-6 cm long; in the middle are knobbed whelks (Busycon carica), and the little one is about 7 cm long; at the bottom are moon shells (Polinices duplicatus), about 6 cm in diameter -- the little bivalve in the center has a moon-shell bore hole in it -- many of the shells on the beach bear this evidence of moon-shell predation.