I would be surprised if it lasted a more than a month in a tank!!
Here it is direct from wetwebmedia:
Collecting Sand Dollars... Best Left at the Beach. - 6/7/07
If I bring live Sand dollar from the beach, and quarantine it, can I put it in my reef tank?
<Greetings, Mich with you tonight.
Can you or should you? Sand dollars generally don't do well in home aquariums typically starving after a few months. They require a lot of sand, approximately 10 sq ft of surface area for a sand dollar 4 inches in diameter. They also need a sand bed at least 4 inches deep, and can be suffocated by fine sediment and aragonite sandy muds found in some reef aquariums. Subtropical sand dollars will not survive at normal reef tank temperatures either. Generally, I think it's best to leave the sand dollar at the beach. Though I am glad you mentioned the quarantine part! Mich>
I'm not A.D.D., I'm just . . . Hey look, a squirrel!
34 Gallon Solana/Current USA 150 HQI & 2 X 65 Watt PC Actinic/(2) 6025Tunze Nanostreams/Koralia Nano/