Presenter Caroline Noonan and Dr Ian Mitchell of the Geological Survey of Northern Ireland go searching for the remains of a lost ocean.

Here at Coal Pit Bay they uncover evidence for its existence in the rocks which once formed the sea bed.

This slatey, mudstone is a sedimentary rock formed from eroded material such as sand, silt and clay which was then carried out to sea and deposited on the ocean floor.

Within the rocks they find fossilised marine life known as graptolites which lived in this ocean 460 million years ago.

The name translates from the Greek as ‘written in the rocks’ as the appearance of graptolites is often compared to a pencil drawing on a rock.