I went fishing at the mouth in the Mississippi last weekend, very muddy with all of the open spillways, and very poor fishing.
But I also went collecting! In general, the pickin's were slim, but, thanks to your advice, I pulled the net through shell debris on 1 of the barrier islands and brought home 4 or 5 baby skillet fish, 4 or 5 small naked gobies, and two baby code gobies, along with an assortment of grass and regular shrimp, a couple of live oysters, and some Widgeon grass. Everyone else thought that the trip was a failure, but not me
I also brought home some loose oyster shells and did practice gluing them together with both gorilla glue and with an industrial strength hot glue gun. I am eager to see how the 2 techniques compare in terms of strength and longevity. I hope to create a work of art similar to yours eventually.
An oyster shell I had glued together last year fell apart soon thereafter, using gorilla glue. To be fair, I had only glued it at the hinge point, and I have some rather large hermits that crawl across it. I was very disappointed at how easily the retained glue could be picked off the shell, though. It does not bode well for long-term results. That oyster was amongst the ones I reglued yesterday, much more generous with the glue.
Have you tried gel style super glues? Or straight silicone? Always worked for me in the past and no impact on the water quality after a 48 hour wait. Not sure if I need to wait that long but I always do.