I was doing student summer job for a month in Crimea sometime in 70s. We were building dwellings for locals. The walls were made of stone that was billions of s

I was doing student summer job for a month in Crimea sometime in 70s. We were building dwellings for locals. The walls were made of stone that was billions of shells cemented together. It was very soft and we were all covered in dust. In combination with the summer heat it was awful.