Ace905 writes "For years the razor sharp beak Squid use to eat their prey have posed a puzzle to scientists. Squid are incredibly soft and fragile, but have a beak as dense as rock and sharp enough to break through hard shells. Scientists have long wondered why the beak doesn't hurt the Squid itself as they use it. New research has just been published in the Friday Edition of "Journal Science" that appears to explain the phenomenon. A detailed article is available online at the CBC web site.
One of the teams researchers described the squid beak as, "like placing an X-Acto blade in a block of fairly firm Jell-O and then trying to use it to chop celery." — illustrating just how bizarre this appendage appears to be. Careful examination shows the beak itself is actually formed in a gradient of density, becoming harder out towards the tip of the beak.
Understanding this gradient relationship may revolutionize Engineering, anywhere "interfaces between soft and hard materials [are required]." One of the first applications researchers imagine would be in Prosthetic Limbs."