In the invention the growing surface of an apparatus for growing invertebrates is increased by a body or bodies (202) located in a growing chamber (201). When food is added to the growing chamber it is spread over at least some of the surfaces of bodies and the inner wall (203) of the growing chamber. This means that the area where invertebrates can grow is increased. The body or bodies are movable with respect to the inner wall of the growing chamber. This allows mixing the added food and other compounds in the growing chamber and it keeps air routes between bodies open.