Is this Cocona? Help identify if not!!!

[Daintree]

I got some fruit at a fruit stand in Colombia and planted the seeds.
One is definitely Lulo (Solanum quitoense).
The other one, pictured below, with my extremely limited Spanish, I thought the vendor told me was Cocona ( I even had her write it down to make sure).
The Lulo thrived, but the Cocona plants died, so when I started looking for replacement seeds, nothing looked like what I had brought back.
So is this some sort of weird purple Cocona (Solanum sessiliflorum), or something else? The fruit was about two inches across and smooth. The leaves of the plant were large, and looked very similar to the Lulo leaves, without the purple spines.
I would love to find seeds of the purple fleshed variety, as it was very creamy and tasty!

Thanks!  Carolyn

[shot]

Do you have a pic of the plant?Very odd,looks more like a star apple ,sure is interesting.

[Daintree]

It is not star apple (caimito), as I bought some of those also, and the seeds and plants looked way different. 
The seeds from this fruit were definitely like tomato seeds, that is why I bought the "Cocona" i.d. from the fruit seller.
Here is a pic of the plant.

[shot]

Someone on here must be heavy into solanaceae?How did you like the taste?Very interesting fruit.

[Daintree]

It was very delicious, sweet and a little tangy.
SOMEBODY must know what this is!

[Oolie]

The leaves look closer to physalis or nightshade than to cocona or naranjilla.

Interesting find.

[Daintree]

But they got very large, almost a foot across.