This is nature writing doing what it does best: leading with delight and landing on unease. The piece opens on a rock pool in Falmouth, where a citizen-science bioblitz run by the Rock Pool Project turns up a rainbow sea slug — a candy-coloured Aeolid nudibranch typically found off Iberian coasts, first recorded in the UK off the Isles of Scilly in 2022 and now establishing itself in the bays of Cornwall and Devon. The writing earns its enthusiasm. The slug is described as "a piece of gaudy costume jewellery," its cerata a "mane of blue finger-like projections topped with yellow and orange," its departure likened to "an overdressed performer late for a carnival." These are specific, sensory images — not the generic adjective-stacking that plagues a lot of nature prose. The author ran across slippery seaweed boulders. You believe it. The structural move is quiet but effective: the slug's beauty is the hook, and the warming-seas context arrives mid-piece without fanfare. The species spread north as waters warmed. Marine biologist Ellie Maynard reports seeing upwards of 20 since her first encounter last Christmas. "It has been really rapid how they have grown in number." The piece doesn't lecture — it lets the velocity of colonisation do the work. A second rarity, the hair curler slug, gets a brief cameo — first reaching the UK only last September. Two subtropical species establishing UK toeholds within two years is a data point that doesn't need editorialising. The Country Diary format constrains what can be done here. This is a few hundred words of observation, not a reported feature. There's no space for population ecology, thermal tolerance ranges, or competitive dynamics with native species. That's a limitation, not a failure — the format is what it is, and this entry works well within it. The citizen-science framing matters. The Rock Pool Project's monthly challenge turns casual beachgoers into survey participants, and the piece models what that looks like in practice: communal excitement, expert context from Maynard, shared wonder. It's a minor but real contribution to scientific engagement. The book plug at the end ("Under the Changing Skies," Guardian Faber) is standard Country Diary apparatus. The piece stands without it.
