How common are tomato 'sports'? I have one on an Italian tomato plant which
has 9 or 10 typical slightly elongated Roma-like tomatoes, and one very
different broad plump and 2-3 times the size of the others? Color is just
beginning to turn. Is this common or should I get excited?

I can't answer your questions, but I recommend you save the seeds if
you like those "sports."

A decade or so ago, one of my "Sweet 100" plants produced tomatoes
that were slightly larger than the others. I saved the seeds and
planted them the following year. Been doing that for, as I said, a
decade or so.

This year, what I call my "golfball" plants are producing tomatoes
that are slightly more than 1.5 inches in diameter. That's about
three times the diameter, IIRC, of the original "Sweet 100" tomato.

vince norris