The oldest mushroom found in amber is from 90 million years ago—a Cordyceps. Scientists recently discovered a fossil first uncovered in 1859 and named Prototaxites, dating back more than 420 million years, a time when the tallest plants were around 2 feet tall. Prototaxites was 3 feet tall laying down, but if standing was nearly 30 feet high. In either case it would be the tallest organism on land...and it was a giant fungus!