Grapefruit bigger than your head

The other morning, I hopped onto the scooter and raced down to the local fruit market before it got too crowded with people. Sitting at his usual stand was an old man that Krista and I bought fruit from often in the fall but had disappeared. He always seems happy to see us and throws in some extra fruit or gives us new fruit to try. Right now, citrus is king. Oranges, kumquats, and pomeloes/grapefruit abound. It is my understanding that grapefruit and pomelo are two different fruit and we have typically had little luck finding tasty pomelo. My parents are visiting and I saw a huge yellow fruit that I purchased to try.

I was pretty sure it was a pomelo but upon cutting it open it was quite juicy instead of the typical dry interior of a pomelo. As we dug it to mondo, fleshy chunks of fruit the consensus was grapefruit.