Slower than watching grass grow

There is one experience available which is slower than watching grass grow – watching Stromatalites grow. What are stromatolites, you ask? Stromatolites are layered limestone rock built by single-cell cyanobacteria which trap and bind sediments. In lay terms – they are rocks which are living and growing. The cells are postulated to be similar to the first forms of life on earth. If you hang around long enough, you’ll actually see these things grow in size!