(CNN) A 22-pound rock that has been propping open a door in Michigan for decades turns out to be a meteorite valued at $100,000, according to Central Michigan University.

Mona Sirbescu, a CMU geology professor, gets asked all the time by people to examine the rocks they bring her -- but none ever turn out to be an official space rock.

"For 18 years, the answer has been categorically 'no' -- meteor wrongs, not meteorites," Sibescu said in a statement from CMU on Thursday.

But that all changed when she was asked to examine an oddly shaped large rock that a Michigan man, who didn't want to be named, had had in his possession for the last 30 years.

"I could tell right away that this was something special," Sibescu said.

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