The geological composition of the calendar rock and the menhir are different, indicating the monolite was cut and brought to the site from elsewhere.
"This obviously reinforces the sacrality of the site," La Spina said.
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At least two other holed stones have been found in Sicily in the past.
"The newly found calendar rock appears to have been made by the same hand that carved the other two rocks," archeo-astronomy expert Alberto Scuderi, regional director of Italian Archaeologist Groups, told Seeker.
Scuderi discovered the two holed stones near Palermo.
"One lined up with the rising sun at the winter solstice, the other produced the same effect with the raising sun at the summer solstice," Scuderi said. "For this reason, I believe that another holed calendar stone, marking the summer solstice, may be found near Gela."
According to Giulio Magli, professor of archaeo-astronomy at Milan's Polytechnic University, the finding is very interesting, especially when associated to two holed stones found in the past.