More big blooms

I have a way now to tell which are true megablooms, and which are just big blossoms. Or at least I think I do, because I'm making this up. I counted sepals (the green petal-like things) on several of the varieties that I'm growing, and it's almost always 7 or 8. But on the megablooms, or what I assume to be megablooms, I've counted 10-14 sepals.

Captain Marvel:

 

 

Big Stack:



BTW, my Zaczilla is a beast. I had to cut out 3 tomatoes and several large branches today to keep it under control.