over a square metre and weighed up to around 20 kg xenophyophores, protozoans of the phylum foraminifera, are the largest examples known, with syringammina fragilissima achieving a diameter of up to 20 cm (7.9 in) nummulite, foraminiferans valonia ventricosa, an alga of the class chlorophyceae, can reach a diameter of 1 to 4 cm (0.4 to 2 in) acetabularia, algae caulerpa, algae, may grow to 3 metres long gromia sphaerica, amoeba, 5 to 38 mm (0.2 to 1 in) thiomargarita namibiensis is the largest bacterium, reaching a diameter of up to 0.75 mm epulopiscium fishelsoni, a bacterium stentor, ciliates nicknamed trumpet animalcules bursaria, largest colpodean ciliates.