HedgeMogs
Castiel appeared in a seemingly normal street, his ink black hair ruffled by the wind. As he set off down the road his trench coat flapped behind him offering little protection form the wind, Castiel didn't seem bothered by this he was too busy looking out for any demon omens. He was currently searching for the king of the crossroads, a demon he believed was named Crowley. When he suddenly heard a voice saying "I'm telling you, HedgeMogs exist!"
Cas turned around abruptly his tie fluttering in the wind to see two teenage girls on the other side of the road who he had not noticed before. What was a HedgeMog? Was this some kind of demon omen? The taller of the girls who seemed to have made the previous comment continued, "They live in jars and come from Mars and when they arrive on earth they protect hedges from cats!" Cas scratched his head making his black hair even messier than before, there was no creature in the world that protected hedges from cats, what would be the point of such a creature and last he had checked Mars was inhabited by a race of small insect like creatures that had never made their way to earth.
The other girl, the smaller one grinned and said "So, what do these 'mystical creatures' look like then," apparently deciding to humour her friend. Castiel listened intently maybe this would help him identify the creature apparently known as a HedgeMog. The taller of the too grinned and exclaimed, "They look like hedgehogs but they are blue with green eyes, we should try and catch one!"
The rest of the conversation was lost to him as the girls walked out of hearing range. Humans really were strange creatures, maybe he'd ask Dean what HedgeMogs were. Yes that's what he'd do. His search for Crowley forgotten Castiel disappeared leaving a seemingly normal street behind.
A small blue hedgehog like creature scampered out from under a car and ran into a nearby hedge; the humans were on to him, he really had to be more careful.
Based on a weird conversation I had, and a creature I made up.