Armored mud balls are very rare, only being noted from about ten locations world-wide and those are mostly from very rural, mountainous locations. Franklin County specimens, when they are encountered, are sometimes found in locally quarried rocks. This means that they have been removed from their bedrock "home" and can be handled if small enough or transported and displayed. These armored mud balls are in a piece of quarried sandstone, part of a historic bridge foundation (now dismantled) between Turners Falls and Gill. This rock is now preserved in the GCC Geology Path collection. Armored mud balls form when hard clay falls into a stream, tumbles downstream and becomes round and soft and sticky on the outside. Pebbles stick to the rim. This is the armor. Then these fragile forms have to be quickly buried and eventually turned to stone. These Connecticut Valley sedimentary events were happening in the Jurassic Period about 200 million years ago. Lithified (turned to stone) armored mud balls are not only very rare, but the ones in Franklin County are the only ones that can be sampled, held in your hand, or displayed in a museum. This is because they are in quarried blocks. All other armored mud ball examples are in mountain or cliff outcrops and are not able to be removed. Therefore, every specimen of lithified armored mud balls you will see in schools and museums is from Franklin County. They are not only fun and intriguing to see, they are truly unique.