There is no spoon green dot. It’s an afterimage from seeing the pink.
Things to add — if you look away, you’ll see green afterimages. Also, if you stare at any of the pink dots for a while, they (or the rest) will still tend to disappear. When you stare at one point, images can fade, especially if they are dim and away from the point at which you are looking, which is a problem in astronomy — you’re looking at a dim star, and it has a tendency to just disappear. This, I’ve learned, is called Troxler’s fading (the wikipedia page uses this illusion as an example). We normally don’t experience this, because we tend to move our eyes a few times per second.
Update: The “pink, green” link is dead, so try this one : Lilac chaser