Black softshell turtle  The black softshell turtle or Bostami turtle ("Nilssonia nigricans)", previously placed in genus "Aspideretes") is a species of freshwater turtle found in India (Assam) and Bangladesh (Chittagong and Sylhet). It was long believed to be inbred individuals of the Indian softshell turtle ("A. gangeticus" or "N. gangeticus") or the Indian peacock softshell turtle ("A. hurum" or "N. hurum"), but while it is a close relative of the latter, it is a distinct species.In the 1800s it was believed these turtles were brought from Iran to Chittagong shrine pond by Hazrat Bayezid Bostami. His turtles he had brought to this pond were treated as sacred and respected by the public. Previously declared extinct by the International Union for Conservation of Nature in 2002, these turtles were found still to exist in a temple’s pond called the Hayagriva Madhava Temple located in Assam, India. Through conservation methods and protection of the species, some of these turtles can be found today throughout the wild, and scientists and environmental biologists are continuing to work hard to preserve this endangered species and their natural habitat. Originally native to the lower Brahmaputra River, the only population ever reliably known consists of a small number of the species in a man-made pond which is part of the Bayazid Bastami shrine at Chittagong, where they are dependent on humans for survival. To the locals and worshipers, the black softshell turtle is known as mazari ("Mazar inhabitant"); specimens from this shrine were used in the first scientific description. In a 2014 survey by Poribesh Banchao Andolon, a Bangladeshi private organization it was found that the amount of oxygen dissolved in the pond water was 2.01 mg/L, whereas the favorable level is 5 mg/L. In 2012, wildlife biologists of the Center for Advanced Research in Natural Resources and Management found a small population in the wild of Sylhet. Two tiny wild populations were discovered in Assam, in Kaziranga and in the Jia Bhoroli River which is a northern tributary of the Brahmaputra. Also, another temple population of these turtles was identified in the Kasopukhuri pond on Nilachal Hill, next to the Kamakhya Temple at Guwahati in Assam. The black softshell turtle has an observably different appearance compared to that of a common turtle.