I LOVE watermelon and have become pretty good at picking out good watermelons. One thing that I’ve come across a few times in the last maybe 5 years is when I cut the watermelon in half, it will have a split in the center and that center will be yellow. It’s like a yellow core/vein or something. It’s kind of rubbery too. Does anyone know what that is?
Have you seen something similar in some potatoes, too? Because there was a thread here a few years ago about that. I don’t remember if there were any suggestions or conclusions in that thread, but the subject came up the other day in a fruit and vegetable shop and the owner thought it was just the fruit or vegetable naturally pulling itself apart from the inside as a result of growth.
If I can just add on to this watermelon thread…
Last night, I saw a packet of watermelon seeds with some other snacks at the Asian grocery store. Product of Philippines, the ingredients were just the seeds and salt. I assume they are roasted.
Has anyone had these? Do you eat the whole thing or shell them like pumpkin seeds?
Similarly, I recently had a curry sauce from Trader Joe’s that used quite a bit of watermelon seed as a thickener. This reviewer points out that it’s used as a replacement for tree nuts. Where else should I be looking for this unfamiliar ingredient?
I was fascinated that ground watermelon seeds were the third ingredient and it seems that they’re used as a thickener. And are sometimes a replacement for cashews or almonds. So it allows them to make a curry that’s vegan and nut-free.
We Tried Trader Joe's Tikka Masala Curry Sauce - DailyWaffle
I ate the whole thing and nothing bad happened to me 
but I suppose that if you have big seeds you could crack them open.
The split is called a “broken heart” or “hollow heart” and it is caused by weather conditions during ripening. Contrary to your experience, the flesh around the cracks are often described as sweeter than the rest of the melon. I think the yellow core may be unrelated to the split.
It sounds like what @Elmer_J.Fudd said, but when I first read the OP I was thinking maybe it was a slight genetic ‘throwback’ to when watermelons were fully seeded and segmented, not all flesh and no seeds like today:
That story is myth-taken. Here is another watermelon painted at around the same time that looked modern:
https://www.nationalgeographic.com/history/article/150821-watermelon-fruit-history-agriculture
And here is a modern melon that looks like the first painting:
Watermelons originally probably looked like this:
Thanks, I appreciate the correction! I hate unknowingly passing along ‘fun facts’ that later turn out to be false. I try to do due diligence on that kind of stuff, but it seemed plausible to me when I first heard it, since so many of our modern fruits and vegetables (not to mention, canine pets) have been bred to be so different than their ancestors.