Hi its not a tomato but toms and potatoes are related. If its gone as far as fruit, then they are just over the ideal time to harvest, which is normally done after flowering. Cut the fruit off and bin. Don't eat them as they aren't edible!

They will be Potatoe seed pods, they do look like small tomatoes.

Nicky you are right to say these are small inedible, indeed poisonous, fruits but their appearance does not mean that the potatoes are past their ideal time to harvest.

This is first time I ever seen fruits on potatoes. So if I plant the nasty fruit, will it grow potatoes then? Also, will it affect any nearby potatoes?

Mrbumble the fruits need to be binned, don't let them get into the ground if you avoid it. Just like a tomato fruit they are full of seeds which will grow on as baby potato plants next year and be right where you don't want them. The fruits will not affect your current crop of potatoes.

If you feel really adventurous, you could plant the seeds in a planned location, and see what you get. That's how Luther Burbank got started. You never know, you could have the seed of the next blight-immune potato!