FUNGI? CABBAGE? These strange shapes continue to attract geologists to Lester Park in Greenfield (Saratoga County) New York! . They're STROMATOLITES — fossilized layers of single-celled algae (or cyanobacteria) that grew in mats beneath the shallow sea covering the Earth about 490 million years ago. Once prevalent around the globe, most cyanobacteria vanished because of a change in the oceans' chemical makeup and the increasing proliferation of marine life that feasted on them. Today, some still grow in the water off the Bahamas and Australia. #NationalFossilDay . 📷: Stromatolite west of Saratoga Springs. (James St. John / Flickr CC)