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 ...

For most organisms on Earth, rocks are objects, not food. But for one oddball microbe, desert limestone seems to have been on ...

Chalk, limestone, shale ... some of the minerals in the sediment harden and form a kind of cement which sticks the grains of the rock together. Look through the slideshow to find out more about ...

CONNOR: Good thinking! I read a bit about limestone on the bus journey. Limestone is a sedimentary rock created by layers of skeletons and shells of sea creatures found in ancient, warm ...

Mysterious tunnels in desert rocks may be the work of unknown microbes, hinting at a hidden world inside marble and limestone ...