Possible Bone Head Please Help Identify

[Teabea121]

I found what I think is a bone head many years ago at Whispering Pines Camp in Franklinville, NY, which is in Cattaraugus County. It was sitting exposed at the edge of a small stream that runs through the camp, on a hill. I apologize for not having scale in the photos. The measurements are: 2.5 cm thick, 4.5 cm across at very top, 3.5 cm top to bottom as pictured.

[Tidgy's Dad]

I don't think that's bone structure. 

Looks like gas vesicles to me which leads me to believe this is slag. 

[caldigger]

Slag for me as well.

[LordTrilobite]

Definitely not a fossil head of an animal.