Can anyone identify this object?
Found in a rockpool, exposed at low tide, just East of the entrance to Plymouth Sound, South West UK.
It feels like it's made of metal. There's a square in the centre with a square hole in it, with smaller squares on each corner, each with a circular hole in their centres.
The four smaller squares each have small circular depressions that appear to have been stamped into the top face on each of their corners. The outer squares might be shaped to curve slightly around the depressions, possibly making the shape of flower petals.
The bottom is plain with no decoration.
None of the markings or holes are uniform, suggesting it wasn't mass produced or made by a machine. It might be wear from being in the sea, but it appears handmade.
The corners have been bent upwards, more on one side than the other.
The sides are about 3cm long.
It's a few mm thick and weighs about 8 grams.
There's a green/grey tarnishing over most of it, on the edges where this appears to have worn through the metal has a gold/bronze colour.
I've looked through the British Museum collection for anything square and metal and tried reverse image searches and some generic keywords but I haven't seen anything similar enough to narrow my search yet.
Any hints as to its age, purpose and/or where to start looking for more information are appreciated.