Stercomata (or stercomes) are extracellular pellets of waste material produced by some groups of foraminiferans, including xenophyophoreans and komokiaceans, Gromia, and testate amoebae. The pellets are ovoid (egg-shaped), brownish in color, and on average measure from 10-20 μm in length.[1] Stercomata are composed of small mineral grains and undigested waste products held together by strands of glycosaminoglycans.[2]
The term “sterkome” was first used Schaudinn in 1899 to describe the balls of undigested food remains produced by the testate amoeba Trichosphaerium sieboldi, the foraminiferan Saccammina sphaerica, and the gromiid Gromia dujardinii.[3] Schaudinn conducted feeding experiments on live individuals of Trichosphaerium sieboldi kept in culture dishes to confirm that stercomata were accumulations of waste material produced as a byproduct of feeding.