Creatures
By now, you must be wondering what kind of amazing creatures inhabited these worlds, right?  Well, now's the part where I tell you!  Quite a few creatures lived outside the nine worlds, in the branches of Yggdrasil itself.  Among them were a solar cock, a serpent and eagle (who represented night and day), and Ratatoskr the mischeivous squirrel.  There was also a serpent named Nidhogg, who constantly gnawed on one of Yggdrasil's roots. 
hey, look! It's all transparent!
AAHH! scary!
These are both pictures of the dreadful Midgard Serpent, Jormundgand.
Hugin & Munin were another pair of creatures, the ravens that told Odin of what was happenning in Midgard.  The boar Schrimnir lived in Valhalla, and his meat was eaten by dead warriors every night.  Come morning, though, his meat always grew back on to his body.  One god, Loki, had three childeren.  One was fenrir, a giant wolf.  The second was Jormungand, a snake that wrapped around the entire world.  The last was Hel, a goddess (Hel was also the name of the underworld Hel ruled over).  Garm was a dog that guarded the gates of Hel, like Cerberus from Greek myth.
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