2 days ago I introduced xenia to my tank. A 20 gal ong 150 watt MH. The xenia were originally from my friends tank but his tank crashed so he gave me his remaining coral. It seems the xenia have not opened up ywt. Its the 3rd day now. It actually seems the xenia shrivled up even smaller then they originally were. I dont know what wrong. Are they dead? If not how would I know corals are dead. Im a newbie to tanks so plz take consideration when giving me answers plz. =/ Thanx