Laver at low tide

Slick strands like glossy hair/oil/treacle/blood/soy sauce
Pasted on the rocks/shiny/clingfilmed/immobile
Waiting for lift-off when the tide turns/the water flows back releasing the stuck filaments to float free, seaweed dancing in the rhythm of the waves again

This is living seaweed - laver, similar to Japanese nori and can be used the same way as an edible ingredient, food wrap or traditional breakfast component. Here at low tide  at Porth Melgan (a mile beyond the popular beach of Whitesands near St David's) the rocks at low tide were coated with the fresh flush of it. It only grows in clean water. No surprise then that seaweed and other products of the sea are being farmed locally and the enterprise is doing well.

Extra; some of the rocks resembled the hairy pates of drowned men.
And, a wider shot of the whole beach