Bacteria?

If its not contaminated they will disappear in a few weeks

If the dots are moving/jumping quickly back and forth then you have bacteria!!! :o
And everything needs to be cleaned out before they hop over and infect other plates in your lab incubator. Also plate some of your media, PBS, and water bath water, to check for the source of the contamination, or to check if these are also contaminated.

I wouldn't jump to an bacterial infection just yet. If your cells stop continuing to grow, or are growing at a slow rate, it may be bacteria. Otherwise it could just be debris. If you can see the blac dots without a microscope it may just be debris.