Starfish are actinoid--that is, they are radially symmetrical.    From Wordnet, Princeton University. 

Far more entertaining would be a tie-in with Los Alamos, and the Metallurgist Chef explaining the culinary wonders of the actinoid series, and why the Oppenheimer Diet is going to be the next big thing in weight loss.    From Wordnik.com.  [Althouse on the road.] Reference

There are fifteen actinoid (rare earth) elements from which fissile isotopes can be produced; uranium and thorium are the only naturally occurring actinoids.    From Wordnik.com.  [Dissident Voice] Reference

Linnaeus necessitated the breaking up of that class into several very distinct classes, so more careful investigation requires the breaking up of Cuvier's "Radiata" (which succeeded the "Vermes" as a sort of zoological lumber-room) into several very distinct and well-defined new classes, of which the Acalephae, Hydrostatic Acalephae, actinoid and hydroid polypes, will form one.    From Wordnik.com.  [Life and Letters of Thomas Henry Huxley — Volume 1] Reference

It is not to be supposed that one could occupy one's self with the animals for so long without coming to some conclusion as to their systematic place, however subsidiary to observation such considerations must always be regarded, and it seems to me (although on such matters I can of course only speak with the greatest hesitation) that just as the more minute and careful observations made upon the old "Vermes" of Linnaeus necessitated the breaking up of that class into several very distinct classes, so more careful investigation requires the breaking up of Cuvier's "Radiata" (which succeeded the "Vermes" as a sort of zoological lumber-room) into several very distinct and well-defined new classes, of which the Acalephae, Hydrostatic Acalephae, actinoid and hydroid polypes, will form one.    From Wordnik.com.  [The Life and Letters of Thomas Henry Huxley]