What started as a summer project for Kathy Silmon and her granddaughters has turned into a viral sensation that brought hundreds -- even some from out of town -- to a Chicago suburb -- all carrying rocks.

The project began when Silmon and her granddaughters each painted a rock and placed them outside with a sign.

"Rocky the rock snake," the sign read, encouraging people to "add a painted rock" and "see how long I can get."

“We wanted to paint rocks, put them out and make a snake,” Silmon told NBC Chicago. “Just something to do. I saw it on a website and thought why not try it and see what happens."

Little did they know "Rocky" was about to grow much larger.

Silmon said word started to spread about Rocky after her daughter made a post on Facebook.

“It exploded,” Silmon said. “We had o

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