"sulfurisphaera" is a facultatively anaerobic, thermophilic, gram-negative archaeon that occurs in acidic solfataric fields. the organism grows under the temperature range of 63–92 °c with the optimum temperature at 84 °c, and under the ph range of 1.0–5.0, with an optimum of ph 2.0. it forms colonies that are smooth, roundly convex, and slightly yellow.