Very nice work!
Kach, those holes are replicating the holes on a real abalone, I have a shell at home but I'm at work right now or I would post a picture.
My brother was a scuba diver and knew of a place where they harvested abalone, apparently they scooped out the meat and tossed the shells in the ocean, he would come hone with bags full of shells.
Alabaster lamp shades at Hearst castle:
