u/MoonShine420Mom

Found in a parking lot in downtown Grass Valley calif. I'm guessing someone dropped it

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Title: Rock identification help: Opaque stone with hard teardrop protrusion (fails steel nail test)Post Body:Hi everyone, I found this interesting rock and am hoping to get some help identifying it.Here are the details and physical properties I've tested so far:Appearance: It is a smooth, rounded river-stone shape. On the top, there is a distinct, smooth, teardrop-shaped protrusion that rises up from a rougher host rock. The bottom is completely smooth and uniform.Hardness Test: I ran a penny test and a steel nail test. Neither the copper penny nor the steel nail could scratch the teardrop or the outer host rock. Both metals just rubbed off on the stone, meaning the Mohs hardness is greater than 5.5.Light Test: The stone is completely opaque. Holding a bright light directly underneath it reveals no transparency or translucency at all.Magnetism: There is absolutely no magnetic pull.Is this a chert nodule, a weathered volcanic inclusion (like basalt), or potentially some kind of fossil cast? Any insights would be greatly appreciated! Thanks in advance for the help.