BigBadBus writes in with a claim by an Italian team that they may have found an impact crater resulting from the 1908 Tunguska explosion over Siberia. The BBC story quotes a number of impact experts who doubt the Italians' claim. "A University of Bologna team says a lake near the epicenter of the blast may be occupying a crater hollowed out by a chunk of rock that hit the ground. Lake Cheko — though shallow — fits the proportions of a small, bowl-shaped impact crater, say the Italy-based scientists. Their investigation of the lake bottom's geology reveals a funnel-like shape not seen in neighboring lakes. In addition, a geophysics survey of the lake bed has turned up an unusual feature about 10m down which could either be compacted lake sediments or a buried fragment of space rock."