The scientific name of the porridge (also called travertine) is “Neogen Limestone”. Limestone is sedimentary rock, whose main ingredient is calcite (CaCO3). It often contains fossils, from which age and origin can be estimated. The mass of the rock has a characteristic cellular structure that includes voids in the form of cannons, large pores and the name quilt.
Areas well known for their poros are Crete and Malta.