Oyster Drill on Olympia oyster (image) University of California - Davis Share Print E-Mail Caption An invasive female oyster drill and her eggs attach to a native Olympia oyster in Tomales Bay, California. Credit Brian Cheng/UC Davis Usage Restrictions Provide credit. Share Print E-Mail 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.