Very interesting. Here's what I found... First the white motion...
This clearly looks like a drop of some form of liquid. Notice the sideways teardrop shape. This is the clear indication of liquid at a high rate of speed. And since it moved in that distance in the time that that the image was shot, I would think its moving fairly fast. I know this sounds bad, but did someone sneeze when this image was taken? Do you have the voice recordings from this time code?
I'm a bit curious about this though. Was someone standing there, or was there some form of reef or something standing by this gravestone? Thats very interesting.