Coloured scanning electron micrograph (SEM) of the shell of a foraminiferan microfossil, Cribroelphidium poeyanum. Foraminifera are marine single-celled marine protozoa that construct and inhabit a calcium carbonate shell composed of several chambers. These are usually penetrated by pores through which the cellular content is extruded to catch their prey. Specimen obtained from the Red Sea. Magnification: x400 when printed at 15 centimetres wide.