Coquina is a sedimentary rock of biochemical origin. It is formed when corals and seashells are consolidated into a rock. The component shells and corals retain much of their shape, and are generally poorly cemented.
Coquina was once used as a building material, although the artificial material of the same name consists of concrete stucco in which pieces of sea shells are pressed.
See Steve's video interview about asteroid capture at Moonandback:|
See Steve's blog
On The Future
A Project Plan for Space Based Solar Power