The world destroyed by the global flood of Noah’s day was very different from today. Here’s just one example: in the pre-flood world, there were towering stromatolite mounds built from algae and sediments washed in by tides. In today’s world, much smaller mounds still exist in a few places. These stromatolites are identical to ones in the past, just smaller. Why?

The fountains of the great deep broke apart and this forever changed the pre-flood ocean environment. The new conditions made it hard for stromatolites to grow like they did before. These algae mounds are a reminder of the flood and a world lost because of sin.