Cool 56-D Lincoln

Hello,
Nothing special about this coin except how I found it! I took it out of the bag and saw the obv almost compleatly white except for some of the letter's on top of the coin which you will see in the scan! No date, turned it over and saw that it was a wheat!
The white stuff which looked like the corrosion you see on some of the 80's cent's! I figured the obv would be pretty much destroyed so I thought what the heck, I will clean it. After some of the white stuff started coming off, I said (WHAT THE HECK)
This is not a joke, The 2 images are of the same coin. I wonder how long the white stuff has been on the coin!! Sorry, so long, but it's only way to explain what happened