Some brittle stars reproduce by fission where they split themselves in half, but like nems, its after they have duplicated a mouth and organs etc. Id imagine if you were able to split the mouth and the central disc evenly, you would probably get 2 surviving brittle stars. I personally wouldnt do it for fun though but it if may help a sick one, then worth a shot.
I only read about 1 person halving a chocolate chip (one half had 3 legs the other had 2). He posted some pics on day one and reported both sides were intact, moving and healing on days 2 and 3 but never supported it with more pics or info so idk if or for how long one or both halves survived. He did try to get the mouth split evenly.
