The top, upward-facing side becomes brown or grayish and is covered in small, dark spots to perfectly match sandy or muddy sea floors. The underside, which rests against the sea floor, remains starkly white or pale. Much like an octopus, the common sole can alter its skin color in seconds to match changing environments. This quick change is controlled by pigment-containing cells in the skin called melanophores. If they disperse, the skin darkens; if they contract and shrink, the skin pales.