Rook,
Grab some sort of Rubbermaid tub that will hold the entire colony, Place it underwater and place the colony inside - don't let it expose to air. Remove the tub with colony and water, Feed large amounts of phyto/mysis and allow to sit for 15 minutes, during the 15 minutes you can gently stir. When returning the piece you can allow to hit air or maneuver it where minimal water returns to the tank. Repeat until it opens over the course of a week. If it does not open after 2-3 attempts its probably in very bad shape.