Just today I salvaged those 2 paddlefish heads. They were the former residents of my city zoo, and rested in the freezer for a loooong time (several years). Unfortunately, their unique long opercula are damaged, since the heads are cut too short. Nevetheless, they should be preserved - we haven't many paddlefishes in Russia. How hard would it be to clean them if bugs aren't available? (I have some, but it's the wrong species, one that destroys insect collections - not a flesh-eater.) I didn't work with acipenseriformes yet, and their skulls surely contain much cartilage. So... hardcore hand-cleaning and freeze-drying? The whole skull needs to be preserved, not just a snout with braincase.