These are mysterious to me...presumably younger than the local Ordovician rock. I don't
know if they are perhaps Devonian. Unfamiliar.
The original source was under the QEW highway in Oakville, Ontario.
I was lucky to discover the same type of rocks used for a promenade in front of some luxury residences.
There are corals, brachiopods, bivalves, trilobites, and various colony creatures.
Little Freddy the parrotlet advised on photography issues.