The red paper band in the photo says “Xinjiang Specialty”. The part of the red paper band that you can’t see in this photo says “Selected Hami Melon”. Wikipedia informs me that this is a type of muskmelon named after a city in—you guessed it—Xinjiang, China.
It’s like a cantaloupe (cantaloupes are also muskmelons), but a bit more oblong like a foo—like an American football, that is. Footballs generally being spheres. I think rugby balls are this shape? Whatever. Here’s another photo.
It seemed crunchier than cantaloupes are, in my experience; the texture was more like that of a honeydew melon. This could just have been a particularly unripe one, though. I mean, hey, what do I know? On the other hand, according to the internet, it’s supposed to be crunchy. Anyhow, it tasted good! That’s what’s important here.
These things are apparently also called ‘snow melons’. I guess it gets cold in Xinjiang.
So, what’s a ‘rock melon’? The orange melon sold everywhere in Singapore at fruit juice stalls is invariably called rock melon. As far as I can tell, ‘rock melon’ is just another name for cantaloupe/cantalope, and whatever you want to call it, it tastes great with prosciutto.
If you think you’ve learned enough about melons for one day, think again. Botanically, they’re vegetables. (They’re related to cucumbers, squash and gourds.) So that whole “what is a tomato, really” debate… you can have it about melons, too.
Also, in case you haven’t stumbled into the parts of the internet that explain how humans have for centuries interfered with the genetics of food crops to make food more delicious, have a look at this article about the watermelon in an oil still life painting from the 17th century.