How to clean a sea urchin test?

[useastcoastcollector]

Hi everyone! I am new and this is my first post. I have been collecting since I was a kid and am happy to find this website. Back to my question - I found a complete sea urchin test with spines and all (empty inside). It is purple and white. However, I need to clean it and it smells AWFUL!! I have read posts on this site about cleaning shells, but I cannot find anything pertaining to sea urchins. How do I clean it without breaking the spines, and how do I remove the smell without taking away its beautiful color? Any help would be much appreciated!