What is this?

Have a tree in my back yard that suddenly after 9 years started growing these on the branches. Can anyone please enlighten me as to what they are?

http://sphotos-a.xx.fbcdn.net/hphotos-ash4/391676_4160041411261_2128959566_n.jpg

 

Those appear to be the fruit of a type of Asian pear. I'm not sure about the variety.

 

Definitely. Liable to be sweet and still crunchy when ripe, more evocative of a melon than a European pear. If they are getting mushy inside they are overripe.