It seems unlikely, but a U of S geology professor believes he has some concrete evidence, and his findings could point the way to new discoveries of oil and gas. Concretions look like smooth boulders and are common throughout the world. Plenty of these formations have been found in southern Saskatchewan, especially along river valleys. Farmers have turned up concretions in their fields and believed them to be meteorites, Pratt noted.
Concretions vary in size, but are most often about as big as a bowling ball or curling rock.
They formed millions of years ago in areas that were once underwater in ancient shallow seas. Pratt said it's thought the concretions grew much like a pearl in an oyster. Calcite precipitated in the sediment, forming a blob that gradually hardened like cement. Estimates as to how long this took vary from less than 1,000 to more than 100,000 years. One of the most puzzling things about concretions is that when they're broken open, many of them reveal an intricately cracked core.