Half right, it's a dried gorgonian skeleton. I'd be careful as it may (if you bought it in a store) be soaked in preservatives or it may rot if there's any of the old tissue (skin) that is simply dried up.
Personally I'd put it in a bucket for a few weeks and then test the water to see if it's leaching anyhing.
I think it should work fine. We had them in a malawi tank at the store I used to work at. If you're really worried just soak it for a week or so and keep changing the water out.