A green pool of water at the largest of the meteorite craters at Kaali on Saaremaa island in Estonia.

The nine <a href="http://en.wikipedia.org/wiki/Kaali_crater" rel="nofollow">Kaali craters</a> were formed between 4,000 and 7,500 years ago by meteorite fragments from an iron meteor that broke up into multiple fragments 5-10 km above ground. The original meteor may have been up to 10,000 metric tonnes when it entered the atmosphere at a speed of 15-45 km/sec, but the fragment creating the main crater was only 20-80 tonne when it hit the ground at 10-20 km/sec.

This was the last giant meteorite fall in a densely populated area, and it left traces in old European folklore (Edda and Kalevala) as well as in written sources (Pytheas and Scandinavian Sagas).