How does Helicoprion Manible Work?

I found this photo @ this page.
Now I wonder how does it work? It is likely inconvenient for gripping anything as its prey.
Any more informantions?

Okay, I could see it being used to grind down shelled creatures. It looks bizarre though. I guess Mollusks where a dominant invertebrate during the Triassic Period.

To add some reference for people who are confused on what |existed" in what time-frame, here is a site I like to look at from time to time. Its not too in depth, makes it easy for lazy people who hate wading through too much text.

Geological Time Scale

Edit: Although this creature was thought to be a Permian Period creature... Maybe Mollusks where dominant back then too but this period ended with "extinction" so who knows...

try these...
kuscholarworks.ku.edu...

paleobiology.si.edu...

fossil.wikia.com...