According to the S-Cool website, limestone is a hard, grey sedimentary rock. Shelly limestone is a carboniferous limestone formed from the fossils of sea animals and plants.
University College London's geology department explains shelly limestone is made up of marine fossils such as coral, which are packed together in calcite cement to form a hard limestone rock. These fossils formed between 200 and 300 million years ago.
Shelly limestone is a tough, almost pure form of limestone, according to University College London. The rock is used in the construction industry, to create cement for road surfaces and as a source of calcium carbonate for the chemicals industry.
Th S-Cool website explains that limestone, such as shelly limestone forms a distinctive landscape called karst. A large area of karst landscape is found in the United Kingdom, particularly in the Yorkshire Dales and Peak District regions.