Raised spot on 1966 quarter?

Theres a raised bump on this quarter what caused it? Theres no dentnon the other side i dont know here to learn lol.

 

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That usually happens when a Clad coin receives exposure to extreme temperature such as heat from a fire.
A bubble forms under the Clad.

 

Oh well worthless but still cool lol that makes since cuz looking at the back its sslightly messed up