This photo of fossils was taken on one of the many limestone blocks making up the Dawson College foundation on the D wing. The rocks are approximately 470 million years old and were formed before there were dinosaurs or even many plants on land. Present–day Montreal was a warm shallow sea closer to the equator then. These fossilized shells were branchiopods, now extinct but very common animals of the past. These brachiopods were probably swept into a shallow area by waves or a current and quickly covered by silt and preserved.