these are the other rocks I found near Lake Ontario enter image description here

  • $\begingroup$ the markings are made by some biological prosses so it is off topic here,so it should be moved to biology section. $\endgroup$ – trond hansen Apr 2 '17 at 8:36

Your rock contains crinoid stems and coral fossils. The circular shape with star pattern is a cross sectional view of a crinoid stem. This patterns gives the fossil the nick name of 'star crinoid'.


Wikopedia has a good summary of crinoids.

Nice website on ontario fossils


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