Rock with circular rocks in it

Found on presque isle in Erie PA along the shoreline. Some kind of fossil? Or just a cool erosion pattern or something like that? Can provide further details if needed, no idea on the mohs hardness scale, it's hard like your typical lake beach rocks around here - hard enough but would probably break if hit with another rock/hammer. It's kinda gritty texture wise, and there's tiny white sparkly bits in it! Thanks in advance!