Give me back my dollar!

During my trip to Tanah Merah sandy shore, I came across something unusual....

Give me back my dollar! from Loh Kok Sheng on Vimeo.

There was a pair of Striped hermit crabs (Clibanarius sp.) apparently fighting over an injured Cake sand dollars (Arachonoides placenta)!

This is my first time seeing such an action. Do they really eat sand dollars? I have no idea! After a while of trying to snatch the sand dollars, the hermit crabs decided to leave the sand dollar alone and they went separate ways. Weird!!