Scanning electron micrograph of a filter feeding appendage (cirri) from a goose barnacle (Lepas). Goose barnacles are non-motile crustaceans that live in the sea attached to rocks and floating objects (such as driftwood) by a long flexible stalk (peduncle). They use their cirri like a sieve to filter water to collect food. Horizontal image width is 4 mm. Supplied by Kevin Mackenzie, courtesy of Wellcome Images.