Diatoms (IMAGE) Virginia Tech Caption Magnified through a microscope, diatoms, which are a type of siliceous microalgae preserved within sediment, helped the researchers determine the salinity levels of the core samples. Photo courtesy of Jessica DePaolis. Credit Photo courtesy of Jessica DePaolis. Usage Restrictions Photo courtesy of Jessica DePaolis. License Original content 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.