Thermococcus stetteri is an extremely thermophilic, marine, sulfur-metabolizing archaebacterium. It is anaerobic, its cells being irregular cocci 1 to 2 μm in diameter. Of the strains first isolated, two were motile due to a tuft of flagella, while the other two strains were nonmotile.[1] Its type strain is K-3 (DSM 5262). It can grow on starch, pectin, and peptides, but not amino acids.[2]