I had a quite large female snapper, it had large amount of fish roe, but nearby it was an interesting piece looking like pure piece of fat, quite hard and solid.

What is this organ and how do you eat it?

I had a quite large female snapper, it had large amount of fish roe, but nearby it was an interesting piece looking like pure piece of fat, quite hard and solid.

Here is a photo, these are the two large white things taking up most of the photo. The reddish thing in the upper-right corner is from a different fish, but I suspect its fundamentally the same kind of thing.

What is this organ called and how do you eat it?