Take a look at this:
Those are called Stromatolites. These ones are in Shark Bay in Australia. You will be forgiven for thinking they look like rock formations. They do, but in reality they are living, breathing colonies of bacteria. Some several thousands of years old.
Fossils of the colonies have been dated back to 3.5 billion years. They are some of the earliest life to exist on earth and are STILL HERE!!!
Now I know it's a drawing, but stick with me. That is the cross-section of Prototaxites. It is no longer with us but the fossil record has these growing up to 26 feet tall. Ready for the crazy part?
It is thought to be a giant fungus. A tree-sized mushroom!
You all should go to Field Of Science. It's a collective of 28 science blogs. Always informative, and always worth the time.