(above) is so similar to Lingulella, the fossil below, that the fossil was originally given the same generic name, Lingula. This particular specimen of Lingulella goes back to the Ordovician era, 450 million years ago. But there are fossils, also originally named Lingula and now known as Lingulella, going back more than half a billion years to the Cambrian era. I should admit, however, that a fossilized shell is not a lot to go on, and some zoologists dispute Lingula s claim to be an almost wholly unchanged 'living fossil'.
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