It did not look appetising and was not; but ‘I am an old man,’ David joked to himself. ‘They are plentiful, and I neither have to run, nor – which I’d surely have to were I fishing – pray.’

He felt, every time, the further surprise, newly, at how a thing that had taken on such ancientness to look at from outside was so bright within.

The pad of his thumb around the smooth inside; the coarse surface on his fingertip. Of all the artefacts he and his wife had collected from the beach he’d take a limpet shell for wonder.

The day seemed indecisive. The breakers of the outgoing tide smushed and drew. Sand martins spun from their tunnels in the cliffs.

Every so often there was a ticking pitter-patter as the low breeze rattled the dry seaweed.

There had been another August storm.

It had washed the sand from the foundations and fallen rubble of two houses that had recently gone onto the beach, and from the skeletal groyne that stretched into the sea.

Against the shifting contours of the shore, the pilings of the old sea defences looked ancient and immoveable. Pitted and barnacled and hung with algae.

David considered that the principles, of how to build a structure to hold back waves, were the same principles his team had used to build footings for the pipeline, all those years ago. Before they had a train to carry water to the city.

That had been his life. The engineering of support. Holding things back. Or holding things up. His wife, Helen, joked he should have designed bras.

He took a few more limpets. Where they were gathered into a family circle on the pilings, he could not take them. He never could. But he was even more conscious now of how it must be for one of a loving group to be knocked off the rock.

That was the hardest thing. Trying not to think of them, his family circle.

At least for the limpet everything seemed fine until that sudden tap from nowhere.

He stood and helped himself to a small diamond of liquorice from the tin he carried. The flavour sat well with the salt air.

He was patient with the stiffness in his back, knowing it would loosen as he walked.

The bright collecting bag was full enough. Helen was right. More sensible to use the gaudy colours now their eyes were going. He’d conceded this the third time he’d lost his grey canvas sack against the stones.

‘You don’t need camouflage for limpets.’ She had a point.

As he headed off the beach, David stopped to watch the sand martins stall and speed along the brow of the collapsing grey cliff.