In 1955 Francis Tully found a fossil 50 miles south of Chicago that looked like “an obese foot-long earthworm with a trunk and a spade shaped tail”. See below.
When Mr Tully brought his discovery to the field museum, where they had no idea what it was either (but they named it Tullimostrum gregarium, which is latin for “Tully Monster”). Or what it might be related to. Or what animal group it belonged in. What they did know was that this strange monster wasn’t rare, in fact specimens started cropping up all over the place.