Looks like a very unhappy nepthya of some sort. Possibly stereonepthya, which is still somewhat hard to keep but easy compared to dendros, scleros.
Not an easy coral by any means. It could well be a Scleronepthya, and it probably is, in which case you will have a very hard time feeding for it, as it is azooxanthallae.
If it is a dendro, yikes. No matter which of those it is it will require planktonic food supplementation on a regular basis.