Is this goniopora still alive or should I toss it, been in tank for about 3 weeks and has never opened up once looked the same since the day I put it in.
It looks like there is still flesh on the skeleton, so it is possible for it to come back, but you probably need to correct whatever it does not like about your tank.
Looks rough I will admit. This is either a hit and miss with your piece unfortunately.
I have had my first coral being a green gonio, and it was like this for at least 3 months never extending etc, amazingly after everything else was happy only then it has started to 'bloom', Just did a transfer of this guy to my new 60 gallon that was cycled for only 1 week that I am sure is not super stable and a self sustaining eco system so expected him to sulk back to his old ways, amazingly hes full bloom in the new tank today morning checking on him.
The next scenario unfortunately is that he will sulk as your photo and unfortunately may start dying. Even still just leave him alone and dont touch him whatsoever his surviving parts may start to bloom and the rest will just degrade away. Remember to run some carbon or sorts as they tend to release toxins from what I recall reading once upon a time.
You may also want to check if the rock he has encrusted on below is not degrading and crumbling, have lost one gonio that was trying to bloom but his edges started dying, on further inspection realised the rock below him was just crumbling away thus moved him 'surgically' to implant on a new piece of rock. Started to show initial blooming from the polyp however fkin shrimps kept steam rolling over him and he basically gave up on life.
Alot of factors come to play but boiling it down A) check rock below is not crumbling, B) leave him alone like he doesnt exist in your tank and dont touch him, C) Try to use this product - Goniopower it has also worked for me and the rest of the tank is in love with it D) high flow/low flow positioning, honestly neither has made a difference to how they have felt in my opinion