Testing chip
After opening a bag of chips, or “crisps” as the OP puts it, they found a tiny blue disc inside. It looked like a bottle cap but was made of ferrous metal and had weird writing on it that would indicate otherwise. Instead of tossing the blue object out, they felt that they needed real answers. Perhaps someone on Reddit could provide them with a clue to their chip-stery (sorry).
And someone did. A commenter claimed that the blue object was a testing chip that manufacturers use to test their metal-detecting machines. This bag was not supposed to exit the manufacturing plant, but somehow, it ended up in the OP’s hands.