I was inspecting my 1977 Johnson 70 HP prop today, and noticed some orange(rusty) debris inside the prop where it exhausts. The pieces are really small, like grains of sand to perhaps a partial grain of rice. They appeared to be stuck, like they had been there a while, since there was rust on them. I scraped them out, gathered them in my hand, and applied a magnet to them, they are magnetic. What would this indicate? 
