Hollow Interior (image) University at Buffalo Caption This pillar, with its hollow interior, was likely created when lava cooled around a column of water, researchers say. Credit Tracy Gregg Usage Restrictions This image may only be published with news reports covering the research described in the associated press release. The image must be credited to Tracy Gregg when used. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.