There are many advantages to home educating Junior, but one of our favourite things is being free to go outside whenever we like. During the winter months, good weather and daylight coincide so infrequently that we nearly always drop everything to make the most of it. Today, Junior wants to explore our local beach and dig in the sand, so we grab our wellies, spade and camera and set out with the low morning sun glimmering from behind the clouds.

Spring comes earlier in Cornwall than it does further north, and the signs are there even though the days are still cold. The herring gulls have already moved back onto the roof-tops in our neighbourhood, and some are sitting on empty nests to deter others from moving into their territories. Buds are tightly wrapped on the hedgerow plants, waiting to open and a few hardy wildflowers are already blooming.

We hear the fulmars honking to each other on the cliffside above Plaidy before we see them. When we stop at a viewspot to look across to the Eddystone lighthouse, a male fulmar glides towards us on stiff wings before circling back to land on a ledge and touch beaks with the female that is resting there.

In the rock pools, spring is even further ahead and I have been finding sea slug spawn for a few weeks already. ‘Sea mushrooms’, the holdfasts of seaweed are appearing on the rocks and beginning to sprout from their centres. Colourful colonies of star ascidian are budding and spreading across the rocks. On one a flatworm is grazing, while another young colony is being visited by a hungry 3-spot cowrie.

The tide is wonderfully low so we scramble out to the furthest rocks we can safely reach. Junior discovers anemones and sponges. A tall rocky gully is coated in every colour of sponge, sea squirt and bryozoan, and we peer closely at their strange forms.

I spot an overhang that plunges into a pool. Even though I can see it’s too deep for my wellies, I wade in, balancing from one submerged rock to another, feeling a cold trickle down my shin as the water overtops my boots. At the edge of the rock the water is still precariously high, but I have noticed some dark, frilly tentacles in the water. Several sea cucumbers are lodged in cracks in the rock here and are busy feeding with their extended fronds. Junior crawls over the rock to get a better view of this unusual sight.

Edging our way through the narrow rocks, we reach the very edge of the sea. We are sheltered a little from the waves by a rocky reef further out, but the waves are still surging back and forth. In a hollow I can see a young common starfish. I tease it out of its hiding place and Junior holds it on his hand while I take photos.

Despite its name, this starfish is nothing like as common on our beaches as the other species we see here, preferring the deeper offshore waters. Junior takes a good look at its colours and its tube feet before placing it back where we found it.

We cross the rocks to the next beach, where Junior begins his sand-mining excavations while I take a walk along an old sea wall in the hope of taking a photo of shanny. These fish hide in holes out of the water while the tide is out and there are usually plenty in this wall. Of course, there are none in accessible places now that I have come to look for them, so I carry on across the beach to take photos of the lugworm casts that litter the muddy sand here.

I am about to go back to see Junior’s work, when I see movement in a shallow pool. It looks as though there’s a tiny geyser beneath the surface throwing the sand up in a constant jet. There are several animals that like to bury themselves here, including some quirky species of prawn, but this sandy pool near the low tide mark makes me think of something else. I crouch by the pool for a few minutes without moving, scanning the sand before I see what I’m looking for. A small, sand-coloured fish is sitting unmoving in the shelter of a rock. I know it will be a weever fish.

Trying not to scare the fish away, I cross to the other end of the pool. It sticks its ground, watching me through shining eyes set towards the top of its head. Even as I lower my camera into the pool, it stays perfectly still, so that I can see its gaping mouth and moving gills. The mouth is unlike that of most other fish: the opening is nearly as high as the fish’s eyes and is hinged at the bottom like a tall flap. Inside it, I can see some spindly, crooked teeth.

I have no bucket and this fish will bury itself in the sand in an instant if I disturb it, so I just watch, putting my camera as close as I dare to frame the fish’s remarkable metallic-green eyes. Although the dark fin on the fish’s back is folded down now, it is made of venomous spines that cause painful stings to bathers in the summer.

Junior emerges from the hole he’s dug to look at the photos and do a beach clean before we head for home in the last of the day’s pale sunshine.