No idea maybe the rocks were on top of the maybe loose rocks then magma got in between the rocks and it turned into a large rock no idea cool rock thx for sharing
Jolteon
Since it's Thursday and I know EVERYTHING on Thursdays here's what it is. It's an ancient tortoise cooked in the shell when it couldn't outrun the magna!
My thoughts are that the specimen was originally dried, cracked mud in or very near the entrance to a cave. That Calcite or other form of Carbonates flowed in the cracks, the specimen then hardened into stone/rock and then rain and/or wind erosion weathered away the hardened but softer mud, leaving the harder Calcite/Carbonate protruding above the specimen's surface. Note: Calcite and other forms of Carbonates are what create Stalagmites and Stalactites in caves.
Well that looks really weird. Not that I know what I'm talking about--but I suppose most igneous rocks are pure igneous and spend most of their time in the mantle or upper crust slowly being very hot and mixing and growing; yet there has to exist some "shock zones" where igneous extrusions are hot enough to infiltrate and alter local in situ rocks but not hot enough to get beyond a quick alteration. Maybe this is one of the rare "igneous meets and alters some mud flat or sedimentary rock enough to change its atomic structure via heat but not enough to fully develop/melt/mix with it" or uh something. If my theory is right I think any crystals (in the "core" in the exposed middle) would be extremely small--microscopic, due to a very quick relative time from introduction to cooling.
If none of us dunderheads can answer the question I'd suggest trotting in to a local college or university's geology department and presenting it. They might be as interested and baffled as I am.