Foraminifera. Coloured scanning electron micrograph (SEM) of foraminiferan microfossils from Barbados beach sand. Microfossils' are roughly 0.05 to 2mm in size.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. Magnification: x 60 when printed at 10 centimetres wide