Black spots on baby's head?

So I was just looking at some of my ultrasound pictures and noticed that on my 10 week pictures, the baby has a black spot on it's head. I didn't really notice when I got it done, so never asked the dr. I have my 20 week ultrasound on Wednesday and will get to see the baby then, but I was just wondering if this is normal. Thanks!

Maybe its the brain? My whole babys head is black because you see her brain. But im not sure what it could be.

it is the brain

I went to yahoo images and looked for 10 week US pics and there was quite a few that had the same dark spots. and a chart indicated it was the brain

so you are normal  

Thanks! That's comforting! I went to google and looked for images and couldn't find any with the spots.