BIOHERMS (from the Greek words "bios" (life) and "herma" (underwater hard rock, hill) * EN: bioherm, organic mound; DE: Bioherme; FR: biohermes; ES: biomasa; RU: биогермы) are the calcareous mounds and hills at the bottom of the seas and lakes, which have been formed by the attached organisms (corals, sponges, bryozoans, algae, and others), which are depositing the lime, and are retaining the fixed position after the death. The dimensions of bioherms are from several centimetres to hundreds of metres in height, and up to several kilometres in width, the shape is from the lenticular one to the stock-shaped one, and, respectively, there is diverse the steepness of the slopes and contacts with synchronous sediments, the thickness of which is always less than the thickness (height) of the bioherms. They are characteristic for the reef facies; they usually serve as the base during the formation of the reefs. They may be found among the marine and fresh water sediments.