Gravel, on the other hand, is like a melting pot of a lot of different rock pieces, including limestone, basalt, and sandstone. Put simply, limestone is a type of rock that is formed by organisms ...

A compound is a substance that contains two or more elements close elementA pure substance that is made from only one type ... limestone, shale, and sandstone are all examples of sedimentary rocks.

Mudstone, shale, and limestone are examples of sedimentary rock likely to ... Throughout the earth's history, each of the three rock types has been continuously formed and recycled into other types of ...

Fungi can bore through rocks and leave behind tubes, and some types of cyanobacteria also thrive off limestone or marble. It is unlikely that the mystery organisms were cyanobacteria—they need ...