I can only imagine what hitting a large turtle on a fast moving motorcycle would be like. Small dogs are the bane of bicyclists. Large ones might take a bite out of you, but those small ones getting caught up in your spokes can be a total disaster!
As for finding things - there was a short period when riding my bicycle on Sunday mornings I kept finding bibles lying in the road. People getting ready to go to church would apparently lay them on the roof of the car for a moment, while unlocking or whatever, then forget and drive off and the bible would fall at the first turn. I assumed I was being sent some sort of message so I memorialized the events in several paintings, two of which are shown on this web page, about half way down the page:
http://www.zianet.com/jaxart/gallery/gallery1.html
Look for 'Literate Ain't Luck' and 'Last Sacred Cow'