Question: I remember that every tribe has his own symbol, e.g. Benjamin's symbol is a wolf. What are the symbols of the 12 tribes?

(I am especially interested in knowing what the symbol is for Levi.)

Answer: 
Update on the stones of the hoshen / 12 Tribes, and their identification. This information is from my father's book "The Natural Bible: Judaism and the Environment", which will be published (be"h) by Berman House this spring. 

* *Odem*: clearly a red stone. Scholars suggest either red jasper, or carnelian sard (a type of quartz).
* *Piteda*: some sort of yellowish-green stone, probably topaz. Others suggest peridot, chrysolite or perhaps green-yellow chalcedony.
* *Bareqet* - translated in the Aramaic Targumim as *azmaragd*, a loanword from the Greek *smaragdos* for “emerald”. Some suggest beryl (of which emerald is a type). Others suggest the green malachite.
* *Nophekh* - its colour is unclear. Is it supposed to be sky blue? Some suggest turquoise. Or red, perhaps more likely (as suggested by the etymology of *nophekh*)? If so, it may be garnet.
* *Sappir* - a blue gem, but unlikely to be sapphire, even though the words are etymologically related. Most likely lapis lazuli.
* *Yahalom* - even though in modern Hebrew it means diamond, almost no scholars think this is correct. It appears to be a white/moon-like stone. Chalcedony is likely, and others suggest moonstone, amethyst or even jade.
* *Leshem* - apparently similar to *sappir*. Aventurine? Hyacinth? Turquoise?
* *Shevo* - almost everyone agrees that this is agate, perhaps striped or spotted.
* *Ahlama* - this is also fairly unanimous that this is amethyst, and the wine connection makes that even clearer (amethyst was associated in the ancient world with wine, and was reputed to prevent drunkenness).
* *Tarshish* - very unclear, especially since we don’t have a colour to associate it with. We don’t even know if it is the name of a stone or simply a precious gem that comes from the city of Tarshish. Scholars have suggested aquamarine, or some kind of beryl. The Targum suggests a stone associated with (the colour of) the ocean.
* *Shoham* - Most likely onyx, although the Targumim give *burla* or *birlewa*, which means beryl.
* *Yashfe* - again, one of the clearer identifications. Almost all scholars are in agreement that this is jasper. The Targum’s association with panthers suggests that it was spotted or veined jasper.
[Revach.net](http://revach.net/lists/article.php?id=42) has a nice table of the tribes populations, flags, symbols, and camp locations.

Levi's symbol was the Urim V'tumim (High Preist's [breastplate](http://en.wikipedia.org/wiki/Hoshen)). This is based on the Meam Loez (Bamidbar 2:2).