This past weekend, I was at the Fathom Five National Marine Park to see Flowerpot Island. Among hiking to see the large and small flower pots (and within Bruce Peninsula National Park), you can see these layers of sea stacks — a geological landform made of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion — all over the park and island.
These natural structures are made gradually over time through strong waves and erosion of the soil. You can see each layer of the rocks within the stack. This one was sticking out of the ground on our walking path and had lots of moss and even gigantic trees growing out of it.