"Hokkaido stone" is a type of "organic mineral" made of elements possessed by living organisms such as carbon and hydrogen. It is presumed to have been formed by the geothermal heat of volcanoes by the remains of organisms in the strata.
It may lead to the elucidation of the mechanism by which oil is formed. The actual stone will be exhibited at the "Tokachi Shikaoi Geopark Visitor Center" in Hokkaido from the 1th of this month.