This is the embryo just prior to emergence. The egg has swollen with water and turned transparent. I dissected this one out of a blob of A. herberti eggs I found in the bottom of a sample vial - we stripped them off prior to a controlled-mating experiment years ago. I posted it as a "mystery" picture because it was so dramatically unusual, and I was interested in the guesses people might take.
The part I still can't figure out are the sections immediately lateral to the beak and immediately proximal to the prothoracic legs. How that "puzzle piece" articulates into the emerged nymph, I can't tell.