That's a Scleral Ring and helps to keep the shape of the eye in fish, many reptiles, and birds. Fish don't have round eyes (they're shaped more like M&Ms or chocolate chips), and the ring helps support the shape when swimming. Most rings are just cartilage, but fast swimmers often have bony rings.

Based on this angle, I think you might be more correct. I thought it was recessed.

It's a scleral ring. Lots of animals have that, many including humans don't.