1) Sedimentary rock
Found on
https://www.crosswordclues.com/clue/oncolite
Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by cyanobacterial growth. Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures. The oncoids often form around a central nucleus, such as a shell fragment, and a calcium carbonate struct...
Found on
http://en.wikipedia.org/wiki/Oncolite
small, often spheroidal, concentrically laminated, calcium-carbonate sedimentary structure or stromatolite that may form in highly saline (salty) waters.
Found on
http://www.fossilmall.com/Science/Glossary.htm
No exact match found.
