First it's a finely laminated cherty mudstone, with a big fracture right through it. The layers don't match up across the fracture, so the fracture ripped the two sides apart some unknown distance. The fracture is filled with several layers of cherty material, first the light-colored stuff and last the dark, flinty stuff with a perfect thin shell of clean stuff around it.
The dark stuff cuts across the older filling. But what you can't see is that the dark layer stops halfway through the stone, with the thin candy shell intact all around it; on the other side is yet another layer of light-colored filling. And while the dark layer has parallel sides, the matching layer on the other side has a pinched waist in it like the start of a boudinage.
And this whole arena of diagenetic activity, this intersection of intersections, was carefully carved, trimmed and polished by tectonics, gravity and surf. Yet the resulting palm-sized nub has lost no significant information; it captures the ancient environment and history of a large volume of rock surrounding it. A whole terrane, a whole land is whittled down to this one specimen. I just don't know what land it was.