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A Stockholm University geologist studied a few rocks the divers picked up from the site, and there wasn't a single alien life-form among them. Instead, there were mostly run-of-the-mill stones that everyone would expect from the kind of glacial basin the Baltic Sea fills. A basaltic rock managed to sneak in among the samples, which is kind of cool, since it's made by lava formation. But it's not really that wacky, considering that glaciers could've easily carried the rock from somewhere else [science.howstuffworks.com]