Acantharians (IMAGE) Marine Biological Laboratory Caption The acantharians are one of the four types of large amoebae that occur in marine open waters. Their fragile skeletons are made of a single crystal of strontium sulfate that quickly dissolves in the ocean water after the cell dies. Credit Linda Amaral Zettler (micro*scope) Usage Restrictions The image will be used only for reporting on this story and that the image will always appear with the photographer credit. License Licensed 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.