There's been several explainations of the Mandalorian Skull on Fett's shoulder bell, but never one for his chest emblem. It's even been incorrectly identified on StarWarsShop.com in some of their product descriptions as a "bantha skull," but that's been pretty much ruled out entirely now. When you see Master Jaing appear in the Star Wars Visionaries comic book, the first thing everyone noticed was that this guy's head is shaped exactly like the Mandalorian Skull (tusks and all). This, of course, gave rise to the question if it was his skull or not. If so, being a sworn enemy to the Mandalorians, even though he was one of their greatest training masters, why do the Mando's use it as a symbol that is universally recognized as being Mandalorian. Mandalmotors uses the skull as part of their logo.
http://starwars.wikia.com/wiki/Mandalmotors
Even the bounty hunter Durge has it painted across his chest armor. This leads me more to think it's the skull of Jaing, since he was his master as well, and it would make sense that he would honor the memory of his fallen master.
http://starwars.wikia.com/wiki/Durge
There are different fan made variations you can find on the internet. Some of them are very ellaborate and well made. Kind of like the icon that Talon is using on the boards here. Did you make that yourself? Looks pretty cool.
Back to the chest emblem, though. At first, it was thought to mean it was the Fett's family crest or something like that, but then it shows
up later, on the ship used by Jaster Mereel and Jango Fett.
http://www.bobafettfanclub.com/multimed … p?pid=1877
http://starwars.wikia.com/wiki/Jaster%27s_Legacy
And then, while watching the DVD of Episode III
something caught my eye, that only a Fett fan would
pick up on. When I re-wound the DVD, sure enough,
there it was. The Clone pilot who is helping Anakin
and Obi-Wan break through the lines to get to the ship
with the Chancellor on it, has this same crest on his
helmet. He's the pilot who says "They're all over me"
and then promptly gets blown to smithereens.
http://www.bobafettfanclub.com/multimed … p?pid=1878
http://www.bobafettfanclub.com/multimed … p?pid=1879
That got me really wondering where it had come from.
However, I was happy to see that they were actually
showing some Mandalorian influence on the Clone
Troopers, besides just the stuff that's written into
the expanded universe.
So far, though, no official canon explanation to what the symbol means has been said. I even emailed the Star Wars.com trivia site the question, but to no avail. No answer came. So, either they didn't know, or there is no answer at the current time. However, I'm sure some author will make up a backstory for it, eventually. Just a matter of time. It'll be be interesting to see what kind of story for it they come up with, as it definitely has to be Mandalorian in origin, but not exclusive to just the Fett's, it would seem.
--Sadriel Fett (BFFC Moderator)
"I'm just a simple Fan, trying to make my way in the universe."