👉 In the context of biogeochemistry, a "stromatoporoid" is a type of sedimentary rock that forms from the accumulation of organic matter over millions of years. These rocks are composed mainly of complex organic compounds such as cellulose, lignin, and lignans, which are found in plant material, such as grasses or trees. The process by which these organic molecules accumulate in stromatoporoids is known as "stomatal respiration."