We went to Oysterville, Washington, this past weekend and got some fresh oysters...at $7/dozen! Tasty! My wife noticed that a couple of the shells are pretty and wanted to add them to our 30-gallon tank. I told her I would ask the experts here as I want to be very careful I don't introduce any bad stuff to our tank or kill our swimming and crawling creatures (no reef yet, just live rock and sand). So is it okay? If so, what needs to be done to them (what preparation) so they will be a safe addition?