Serpentine Nodule
*Septarian
Also this is technically a rock since it is made of multiple minerals - calcite, aragonite, and then the host rock which is a calcareous mudstone IIRC.
That’s okay, I read this post as Serpentine Noodle anyway
Ha! I like it
OMG, I didn't even notice autocorrect got me!
Haha I figured but wanted to point it out just in case. I hope I didn't come off as too much of an "um, actually" jerk! Cool pic btw!