In this photo distributed by the Urals Federal University Press Service a researcher examines pieces of a meteorite in a laboratory in Yekaterinburg on Monday, Feb.18, 2013. Researchers from the Urals Federal University, based in Yekaterinburg, have determined that the small stone-like pieces found near Lake Cherbarkul in the Chelyabinsk region are pieces of the meteorite that exploded over the region Feb. 15. A total of 53 pieces have been brought for analysis to the university in Yekaterinburg. The largest one is one centimeter in diameter, the smallest is about one millimeter.