Anyone know what type of rock this is?

[Springfairy556]

I found it while I was using my metal detector.I like rocks, even plain ones.I didn't know metal detectors went off for rocks.Just curious what type of rock it is?

 

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[DDancer]

First thought was an old piece of oyster shell but you say your detector reacted to it. Looks like something shiny scattered thru the middle. Closer picture might help. As to detectors~ if there is enough conductivity in the mineral a detector will see it. Iron stone, some pyrites, coal and of course silver/gold will give a beep.