English: A stack of Slipper Limpet (Crepidula fornicata). This photo shows six living slipper limpets stacked one atop another, held together by the muscular foot at the bottom of each animal. The stack curves slightly; there is no need to balance in the water because they are nearly buoyancy-neutral. The shells are pale with ochre to sienna markings which do not occur in a pattern. The bottom most animal is a mature female; the others are also females, and are probably younger as one goes up the stack. The topmost individual is the smallest, and is a male. Because each shell has a rounded, convex upper surface (the shell), and a concave lower surface (the muscular foot of the animal), the overall appearance of the stack resembles a grub (a beetle larva).