This morning I came across an interesting story on MSNBC.com that revealed the discovery of a 300 million year-old fish fossil. Ordinarily this wouldn’t be the biggest deal in the world. It’s not the oldest fossil on record — that distinction belongs to an ancient sponge believed to be 635 million years old. It’s not even the oldest fish fossil on record. That honor goes to a fossil found in China in 1999 that’s estimated to be 530 million years old.

The cool thing about the recent find is that it’s a fossil of a brain. This makes it an extremely rare find and the oldest brain (fossil) on earth. Most ancient fossils are from bones, not organs or soft tissue. There’s been some fossilized muscle tissue found here and there, and fossilized kidneys have also been discovered.