Penicillin, X-rays, vulcanized rubber—some of the greatest scientific discoveries happened by accident. Thanks to his love of invertebrates, William & Mary Biology Professor Jon Allen has added another entry to that list of happenstance achievements. Meandering around the mud at the bottom of a tank in Allen’s lab lives the world’s oldest ribbon worm on record. His name is Baseodiscus the Eldest, or B, for short.