  Search for different life-forms elsewhere is the fascinating area of research
in astrophysics and astrobiology. Nearly 3500 exoplanets are discovered
according to NASA exoplanet archive database. Earth Similarity Index (ESI) is
defined as the geometrical mean of radius, density, escape velocity and surface
temperature, ranging from 0 (dissimilar to Earth) to 1(Earth). In this
research, rocky exoplanets that are suitable for rock dependent extremophiles,
such as: Chroococcidiopsis and Acarosporamto are chosen, which can potentially
survive are considered. The Colonizing Similarity Index (CSI) is introduced and
analysed for 1650 rocky exoplanets, CSI is basically representing Earth-like
planets that are suitable for rocky extremophiles which can survive in extreme
temperatures (i.e. as hot as desert and cold as frozen lands). In this work the
in-habitable exoplanets are recognised even for these rocky extremophiles to
not potentially survive by using the CSI metric tool.
