Well, that's definitely an ophiuroid, and it DOES appear to be
symmetrical ie not due to injury... though it COULD be an injury
during development (though I suspect not).
I'm not aware of any 4-rayed species of ophiuroid, though I didn't
know of 6-rayed ones either, until I began to find them! So it could
be a 4-rayed species, or else an abnormality.
But don't ask me what species it is... or genus... or family!