Few city rats have left their mark on the public consciousness — and the urban landscape — like the one responsible for the famed “Chicago rat hole.” (“Pizza Rat” is a notable exception.)

But the Windy City’s “rat hole” may not be what it seems.

New research into the identity of the creature that caused a sidewalk imprint when it fell into freshly poured cement suggests the culprit is an entirely different city dweller.

Much lore surrounds the Chicago rat hole, also dubbed “Splatatouille” during a public naming contest.

No one seems to know when the mark first appeared in Chicago’s Roscoe Village neighborhood, but it’s believed to have been there for at least two to three decades. However, one tweet from Chicago artist, writer and comedian Winslow Dumaine on January 6, 2024, transformed it into a social media sensation: “Had to make a pilgrimage to the Chicago Rat Hole,” he shared in a post on X, along with a photo.

Winslow Dumain

It soon became Chicago’s hottest selfie spot and people left offerings of coins and other items — a couple reportedly even tied the knot next to the mark. Complaints from neighbors led the Chicago Department of Transportation to remove and replace the sidewalk in April 2024.

But a key question lingered: Was it really a rat that made the mark?

The public curiosity about the imprint inspired Dr. Michael Granatosky, an assistant professor in ecology and evolutionary biology at the University of Tennessee, Knoxville, to take up the investigation.

“What a great way to