What's the significance of the watermelon in Sora no Otoshimono? In Sora no Otoshimono, Ikaros carries around a watermelon like a pet and likes watermelons and pretty much anything else round.  At one point she even has a watermelon garden and attacks all the bugs that get near the melons.

What's the significance of the watermelon and why does she carry one around?
I believe there is no significance.

It is just a character trait that she really likes watermelons. Probably for their smooth and round shape.