If you mean the train station in Season 1 Episode 1, there's nothing that I can see from watching it so it could be a glitch from when you watched it. :)

A glitch or Extremis are my best guesses.

Just checked again and there's literally nothing there. It's a glitch on the thread-starter guy's screen. :)

I just realised they put it in to show the Jemma had something wrong with her to shock people didn’t they

@Reallegend99 There's nothing there. Look back into this thread and see that I looked into it.

I remember while watch the show she had something wrong with her can’t remember what there was and her head started glowing maby they removed it

This isn't the same thing.

Ok If u say

Maybe it's just her 200 IQ shining through.

That’s the best theorie ever