Limestone is used as stone building blocks, Limestone is used in the manufacture of cement.
the awesome josh building was made from limestone in 2003
The Houses of Parliament are made out of Limestone.
i have no idea all i know is that the empire state building is made out of limestone in 1931 & the Houses of parliament in london.
limestone
the Empire State Building was made out of granite and Indian limestone. cool huh?
Limestone
St Pauls Cathedral
cement concrete mortar bricks
Most of them were made from limestone often quarried close to the building site to minimise transportation.
If your question is "What do you call someone who uses the products made by industry?", you call him a consumer.
Because the building is made of limestone, and the shells became integral to the limestone as it was being formed, but they don't erode as quickly as the limestone in the rain.
Maybe you are looking for the term "cottage industry".