Mystery Fruit

Its been a while since I posted about exotic fruit; sadly my trips to the grocery store have gotten more mundane and less amazed as I have adjusted to many of the strange sights and smells.  Actually I don't think I've actually posted pictures from the Carrefour here, which I will try to do sometime before I leave. Anyway, on my last grocery trip I stumbled on this mystery fruit which I just had to try due to my never having had it before.  I got lucky with durian and dragon fruit, why not this?

Here it is before cutting it open:

And here it is open:

The consistency was a mix between an apple and a pear, and the taste was somewhere in there too.  The white flesh on the inside was fairly sweet but I made the mistake of taking a nibble of the green on the outside, and it was very bitter.  I actually had a bad taste in my mouth for about an hour after eating!  I still don't know what it is, anyone know??