Why in the world is there a unicorn on the front of Canadian Passports?

I’m going on a trip to England this friday, so I was packing my passport. I was looking at it and I noticed that there’s a unicorn on the front of it! It looks like a horse at first, but if you look closely it has a horn, just like a unicorn. If your not Canadian, here’s a picture: http://magnetiquemtl.files.wordpress.com/2009/02/canadian_passport.jpg
It’s kind of difficult to see on the picture, but it’s there…

Why would the Canadian government put that on the passport? Does anyone have an explanation of this? I think it’s hilarious that its on there..