In our garden where we thought we had planted cantaloupe, next to cucumbers - we have grown something, but we don’t know what it is. So far when we cut one the inside was green. Here are 2 pictures, one from a couple of weeks ago and one from now. Can you guess what it is and how we should know when it is ripe?
It's possible this is an immature banana melon: https://www.superseeds.com/products/banana-melon-80-days-heirloom
Melons are notorious for crossing with other melons or plants in that family, such as gourds, squash, etc. If you saved seeds from a fruit, this may be a cross.
If you purchased seeds or a transplant, this may merely be a mix-up. It happens.