Likely a sterile medium means an uncontaminated culture (food free of living organisms) that will grow only the new bacteria introduced for analysis. Source(s): http://www.thefreedictionary.com/sterile
Stonepelt was Bluestar's first mentor and a very well-respected senior warrior of ThunderClan. It is revealed in this book that he took her to the Gathering on her second day as an apprentice because she had caught a squirrel very well for a new apprentice, and the squirrel had been as big as she was.
Cataclysm Dungeon Guide: The Stonecore. Adventurers will find the site of the Stonecore in Deepholm, wedged on the west side of the Temple of the Earth. A flying mount (or a crafty summon) will be needed to discover the entrance. Earthen Ring Shaman are attempting to maintain the World Pillar and prevent it from sustaining any further damage.