Mysterious Object Found on Beach! (And On Invertebrates)

The other day, when I was out for a walk by the ocean, I found an odd object on the beach. It appears to be some sort of segmented plate from the calcified remains of an exoskeleton. Perhaps it is from some type of arthropod or mollusk (chiton)? Any information would be much appreciated!

The object from the front. It has a very smooth texture with little pits in it. 

Back view of the object. It looks somewhat like a pelvis. 

Side view of the object. It seems to be a calcified plate from an exoskeleton.  

The way this item looks reminds me a lot of a pillbug, trilobite, or chiton. I can't help but to think of the ancient insects and marine creatures from the Cambrian Period that once roamed the Earth. It's amazing how huge insects and invertebrates could grow to be. (One of the largest being an ancestor of the millipede over eight feet in length!) Fortunately, for those who are more phobia prone, bugs this size can physically no longer exist. This is mostly due to lower oxygen levels in today's atmosphere. (Of course, if something happens to the atmosphere in the future giant bugs could return.) Some people also theorize that birds ate larger insects out of existence. What ever the case, large invertebrates are no longer with us except for in horror or sci-fi films.

I used to love to catch and play with these as a kid.

The object I found is most likely from a chiton (which is technically not a bug but a mollusk). 

Terrifyingly gigantic invertebrates dominated the Cambrian.  

Sorry, not possible in today's world. (Science ruins any possibility of an alien bug invasion.) 

Call me weird, but I have always been fascinated by insects and how strange and unearthly they seem. Perhaps its because they are so ancient and I admire how long they have been able to survive on this planet. Insects and invertebrates are the world's most populous species. About 8.7 million are estimated to exist in the world today! Most insects are relatively harmless. (Out of all the species, only about forty are considered venomous.) Many people still seem leerily of them however. Could this be because we are aware of how huge they once were, or that we are just creeped out by how unlike us they are, or how little most people know about them? 

Coincidentally, one of my favorite movies happens to be Nausicaa of the Valley of the Wind (and not only because it has giant insects in it). It is 1984 Hayao Miyazaki film about a princess who must save her world from warring peoples in a post-apocalyptic future. Nausicaa is parable about how human and nature get along (or rather don't get along). The titular character must find a way in which the insects in the spreading toxic jungle and humanity can peacefully coexist because they are dependent on one another. It is truly a great film about learning not to fear the unknown and many subsequent anime and sci-fi films were influenced by it. (If you have seen both Nausicaa and James Cameron's Avatar, for instance, the forests in both films bare an uncanny resemblance to one another.)    

Never question a princess who loves insects. 

James Cameron is a huge Miyazaki fan.