"Woolly Mammoth Tooth" as discovered in river gravel and limestone.  A  Mammoth can go through 'six' sets of molars during it's life as the teeth erodes just from feeding on the high 'silica' content grasses and sedges. Many occasions I have discovered teeth to exhibit a very wide range of typology.  It is the most common fossil discovered in Arctic rivers from the many extinct 'Ice Age' animals of ten to forty thousand years distant."