Natural salt deposits contain microorganisms reported to be up to hundreds of millions of years old. Recent studies have concluded that salt-loving (halophilic) microbes living in ancient surface environments became trapped inside salt crystals and survived in a dormant state within the buried deposits. Protracted survival of microorganisms in ancient salt formations and other materials has redefined views of long-term survival and led to the realization that the biosphere on Earth and perhaps other parts of the solar system extends well into the solid subsurface.