Arrows pointing backwards and wavy letters

In January, when the water is too cold for wading, and the wet stones and sand are cold enough to cause a bone-deep ache in rock-flipping and sand-digging fingers, we behave more sedately than usual, walking upright on the sand, hands in gloves and pockets, eyes peeled for what we can see without stopping and getting chilled.

Sand, water and sky. Patterns in blue and grey. Laurie usually looks up to the sky and the distant snowy peaks. I'm more likely to watch what's in front of my feet.

Duck footprints. Probably mallards. Three toes, and distinct webbing.  Ducks toe in, which makes them waddle.

A duck has four toes; three facing forward, webbed, and a fourth, called a hallux. It faces backwards, is small and higher up on the leg. Sometimes it leaves a mark on the footprint. More often, it doesn't.

Gull tracks. The tip of the hallux left a mark in this wet sand. The footprint is about twice the size of the duck prints above, and the webbing isn't as marked. Like ducks, they toe in.

Heron tracks in soft sand. I don't know what makes those dotted-line furrows.

Heron track with my big boot for measurement. About 6.5 inches. (The heron's foot, not mine.) These are big birds.

Heron track on hard-packed sand. He drags that rear toenail. There is no webbing; the heron is not a swimmer.

Something different; check this out!

Just sand, sculpted by the tide.

But: this was flat, flat beach. Very flat; I want to emphasize this. But look at the photo from a bit of a distance; to me, it looks hilly. From a few steps back, the hills grow into small mountain ranges. And sometimes, when it catches my eye suddenly, I see what looks like letters among the lines. I can't read them; they morph into different shapes with the slightest head movement. (If I'm looking for them, I don't see them.)

What do you see?