Take a ball of mud, apply pressure and time, and you sometimes get a septarian concretion. They can be quite beautiful, I have a pair of bookends cut from one o

Take a ball of mud, apply pressure and time, and you sometimes get a septarian concretion. They can be quite beautiful, I have a pair of bookends cut from one on my shelf. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1313&_nkw=septarian&_sacat=0 https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m... I've seen some big balls of software mud that formed very nicely under pressure too.