Ireland's time under a tropical sea is perhaps best explored here at Streedagh Beach in County Sligo.

We know that our local limestone was formed 350 million years ago because it contains the remains of plants and animals that were alive at the time.

This is the graveyard of a seabed dating from that period.

The fossils along this stretch of coast are probably the best evidence we have in the country that we were once submerged under a tropical sea teaming with corals, shellfish and sea lilies.

Here and there among them you can see a very common type of shellfish known as brachiopods.

Next time you are at the Ulster Museum, check out the large fossil slab at the entrance which comes from here.

It contains large fossil corals of which there are literally millions of well-preserved examples along Streedagh beach.