Black tar lichen or tar?

Black tar lichen or tar?

Observation - Black tar lichen or tar? - UK and Ireland. Description: The surface of many of the rocks here have a covering of matt black between the low tide mark to the edge of the splash zone where it becomes more spotted. I can't see much in the way of form and so wonder if this is just tar?

The surface of many of the rocks here have a covering of matt black between the low tide mark to the edge of the splash zone where it becomes more spotted. I can't see much in the way of form and so wonder if this is just tar?