Substance in sediment (IMAGE) Stockholm University Caption The white substance in the sediments is gas hydrate that hosts a large quantity of methane. The photo was taken during the expedition where samples were collected. The diameter of the sediment core in the middle of the photo is about 10 cm. Credit Photo: Wei-Li Hong Usage Restrictions No restrictions. License Public Domain 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.