Tube Anemone 

The tube anemone creates a tough leathery tube that sinks 2 feet into the sand to shield itself from predators. The tube worn is able to go down into the tube if a predator approaches and then can take the predator down the tube with it. After attacks the tube worn is able to grow back the tentacles it lost. 

http://www.montereybayaquarium.org/animal-guide/invertebrates/tube-anemone