What is this small soft-ish purple circle in the middle of my keyboard on my laptop? Came like that?

It is small, about the size of a pencil eraser. it is purple and soft-ish. It is located between the g and h keys. Its a dell inspiron 4000. I think it's a crumb catcher, like if your eating doritos or something you can wipe your fingers off on it without dirtying up the keys. My boyfriend doesn't think so. Any input?