Grendal's lack of description

It occured to me while I was reading Beowulf that there wasn't a clear description of Grendel. All we know is that he has an arm, which Beowulf rips off. I always assumed that a fuller description would come later, but it never did.

I think the poet might have done this intentionally. In not describing Grendel, he forces us (the readers) to imagine our own Grendel, the terrifying monster who lurks in the swamp by day, venturing forth at night to slaughter the sleeping humans. Each person is free to conjure up his or her own image of Grendel, which would terrify them personally.

~Hannah