The Chambered Nautilus is a marine mollusks with an external shell, which on the underside is plain white, whilst above it is matte white with irregular brownish stripes, a special design for camouflage countershading. Its shell contains a series of separate chambers (fig.), enabling it to adjusts its buoyancy and to dive. It is about 20 centimeters in size, but its seemingly large eyes lack a solid lens and do not actually provide good vision.