Help identifying find

[instantajohn]

After several years away from the hobby I had a day out detecting today on a new site. The site is close to another where I have found a number of Romano British brooches. The only find of note was the item pictured below. It is quite large at 45mm diameter. But also quite thin (only a couple of mm). it is bronze.

I wonder if it is an annular brooch. It has similarities to some terret rings but the thickness and size seem wrong. My gut feeling is that it is pre medieval but I would welcome expert opinion. Thanks in advance for any help.

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[Phantom_Major]

Could be a Terret ring? Very Celtic looking though!