Look what I got

[AJsTank]

A couple 4 inch Sea Biscuits aka sand dollars for my sand bed in the 400

 

[pagojoe]

Cool. It'll be interesting to see how well they do.



Don

 

[Betta132]

If I remember correctly, they're filter feeders most of the time. Tank that big, I bet they'll do pretty well. I hope you get to see them!

 

[Calappidae]

Those are actually heart urchins Family Spatangidae to be exact.

A sand dollar is flat and hard on one side.. and the bottom is fuzzy. These guys are fuzzy all around and are not flat. Heart urchins I occasionally see at my lfs.. they're the urchin version of the sandsifting starfish in every aspect.

Here's an example of a true live sanddollar which is very rarely if ever even collected in aquarium trade.

 

[Betta132]

Live sand dollars look pretty much like that, just flatter. I've seen 'em wild. Even found a baby sand nickel
That makes sense that they're something else... I thought they looked weird, but I supposed they were just some sort of tall sand dollar.