Foraminiferan test. Coloured scanning electron micrograph (SEM). Foraminiferan test from Iriomote Jima, Ryukyu Islands, Japan (Baculogypsina sp.). Foraminifera are marine single-celled marine protozoa that produce (most commonly) a calciferous test (skeleton) which is divided into chambers. Live foraminifera have filopodia that are united in a complex fashion to produce reticulopodia. Known as star sand when found in high concentrations. Magnification: x 25 when printed at 10cm wide