Fossil hunters digging the soil near a creek in north-central Illinois have come across a remarkable discovery — Tully monster. They have found the preserved remnants of a prehistoric creature, which appears to be having a long, arm-like appendage extending from below with a pincer-like mouth and its wide-set eyes pointed towards stalks.

Scott Lidgard, a paleontologist at Chicago’s Field Museum, said the Tully monster, which is Illinois’ official state fossil, beyond doubt was “very, very bizarre”.

Lidgard is responsible for handling of the museum’s collection of 1,800 Tully monster fossils, which is the largest collection across the globe.

So far, no researcher was able to highlight how exactly the soft-bodied creature looked, a notion that changed Wednesday after a related paper was published in the journal Nature. After their study, Lidgard and his co-researchers arrived at the conclusion that the Tully monster had a precursor to a backbone, thus making it a primitive fish, or vertebrate.

The fossils of the Tully monster have been found only in Mazon Creek area, about 50 miles southwest of downtown Chicago, a place that 300 million years ago apparently was a warm coastal marsh along a long-gone sea near the equator.

The first Tully monster was unearthed in 1958 by an amateur paleontologist, named Francis Tully. Thousands of other fossilized remnants have since been found by fossil hunters combing the place, now preserved as Mazonia-Braidwood State Fish and Wildlife Area.

Colleen Schmidt, an office associate at the state fish and wildlife area, said, “Mining faded in the 1970s, and, after decades of fossil hunting, the area does not yield quite as many specimens as it used to. But those who know where to look can still find plenty. They leave with oblong nodules of rock, some of which, when broken open, contain fossils; often it’s plant life, like prehistoric ferns that are hard to imagine on Illinois’ prairie”.