Weird

WE were given some tomato plants several weeks ago, planted in Growbags they are doing as well as cn be expected seeing how chilly and sunless the weather is. Well, this has happened, this was a bunch of tomatos, but they have grown together to make a very large single tomato, we think they want to take over the world! Anyone seen anything similar? Can we eat this thing? It is as big as my fist!
Tow things to note about this Blip, 1st. the sun is shining, 2nd, it hasn't rained( so far) today.....