World bosses aren't normally rares, and this doesn't fit with the described world bosses so far. It's possible, but I'm guessing this guy is just a particularly tough rare spawn.
Hard to say. That area looks very incomplete.
These are the world bosses so far. No mention of a Hydra.
Tarina = Genasaur
Good catch!
Looking at his health amount, that's no ordinairy mob, that's for sure. I'm going to guess he's a group boss, but not on the level of an actual Raid level World Boss. Just an area boss that requires a group, but doesn't have raid mechanics or requires like the classic tank/healer/dps requirements World bosses do (at least at first).
It's likely a ?? boss because he's more than 10 levels higher than you. If you're in Taanan for the entry quests, likely we won't be back there until level 100.
If at level 100 he still has a skull, then he's still 3 levels higher than you (this is known as a Dynamic Level).
This is not a WB, just a lvl 100 rare.
Just checked MoP beta screenshots:
http://i.imgur.com/TKo0hRi.png (Galleon)
http://i.imgur.com/roogP7Y.png (Sha)
Sha & Galleon had the rare portrait. I dont't know how it is on the live realms right now as I'm unsubbed right now.
@FayrenPickpocket Rares are tagged with Level (Elite) or just Level but not with Level (boss)!
And again: I know it's just pure speculation but he COULD BE a world boss.
Gaze into the heart of N'Zoth.
Sha and Galleon had a rare portrait when they were current tier. For whatever reason they changed them to the gold portrait.
Level 100 normal mode dungeon bosses have about ~4m health. With this having 40m it's definitely not a 5 man group rare spawn. Honestly with that health pool seems to be a 10-20 man world boss.
Oh fair enough, I don't remember them having rare portraits. I stand corrected!