Examine the area below the face, see a head with a coal being pressed to the lips - the story of Isaiah being burned by a seraphim. Above that, a face expressing agony - he is being sawed in half, per the order of King Manasseh. But around him, in and out of figure/ground are various faces, women and men, some surprised, some laughing. Topping the fishtails are vignettes of Isaiah receiving visions from God of the possible future, forming his principal message of hope and grace against a wicked world. A couple of birds flank the center, protecting that future.
The clamshell can reduce itself into a seraphim. Behind the face is a boat with a small gold figure stored, lying inside - a common motif for another story, another time.