Rainbow Eyes

I see these tiny little Tephritid fruit flies on burdock seed heads every year. I'm fascinated by their rainbow eyes. They are known as burdock gall flies as their larvae cause galls on burdock plants. The burrs are fully formed, all the little hooks can be seen.

I found something grey, dry and strange down the field and showed it to Ollie. She was very interested and once she started chewing it released a strong fishy smell. I could see what looked like fins but no scales. I'm not very up on fish. I think the only UK freshwater scaleless fish is the eel? Maybe that's what it was. Wonder how it ended up in our field? Something to do with Reynard and his family or Jack heron possibly?