I'll preface my answer by stating that my ideas haven't been well-received here. However your specimen here has very similar traits to a few from my collection and I feel encouraged to share my thoughts. I believe you have a fossilized crinoid or blastoid calyx there. These are ancient Echinoderms related to starfish and sea urchins. There are 100's of Crinoid species alive today, but no Blastoid made it past the Permian extinction. Here's a link to some background info: http://www.fossilcrinoids.com
Both Crinoids and blastoids had calcium carbonate skeletons and the main, central area of both is called the calyx--comprised of a series of bony plates that protected the animals' soft parts, like digestive and nervous systems.
Regarding the type of minerals substituted during the lithification process, I have much less confidence. To venture a guess, the black is Hematite. The yellow a sulphur bearing mineral, perhaps orpiment? Hard to say conclusively with given info. My confidence is very high that this is a fossil. I have handled perhaps hundreds of rocks that share the same physical traits: the raised "loop" you can see--vestiges of arms; the fractured area at the conical end of your piece where the more distal arms have disarticulated and the sunken area of that ambulacral groove is evident. Your first photos are a view of the "tegmen" of this crinoid. The last photo is a glaring example of pentaradial symmetry. To guess, that is where, in life, the stem was connected to this calyx, as most crinoid species were stalked 350-400 Mya. That's around how old your rock is, I declare.
My photos are of a similar specimen, larger, about a 50 cent piece, wt is a bit above what you'd expect- sorry, I'm a bit pressed for time to obtain greater detail. This was found approximately 10 feet down from ground level. The ground however was a 15-20 foot elevated tract of land that was lakeside in Clear Lake, IA. North Central part of the state and just inside the SE border of the Des Moines Lobe glacial landform. I'm an excavator and we were digging a basement in virgin soil. At depth, sandy with pebbles and rocks up to 10 inches. I don't recall any here but glacial erratics are common near-by. Essentially in all NC Iowa. FWIW.