Every August, the town of O Carballiño holds the largest octopus festival in Spain. Diners gather around colossal copper pots while pulpeiras cook through between twenty-five and thirty thousand kilos of octopus across the festival, lifting the tentacles, slicing them onto wooden plates, dressing them with nothing but olive oil, coarse salt, and paprika. It is the totemic dish of the region, polbo á feira, octopus of the fair, served in Galicia for more than five hundred years. And the strange part is that O Carballiño sits eighty kilometres from the sea, in Ourense, the only province in all of Galicia with no coastline at all.

A coastal animal became the signature food of the one corner of Galicia that never touched the coast, and the reason is a small piece of medieval economics. The monastery of Oseira held port rights down on the Rías Baixas, and octopus, dried for preservation, was paid to the monks in kind as rent on those holdings. The people of the inland parishes that belonged to Oseira were the ones who carried the dried octopus up from the coast, prepared it, and sold it at the markets and cattle fairs. The dish is called “of the fair” because the fair, not the harbour, was where most of inland Galicia ever met it. The octopus went where the fresh fish could not, for the same reason the salted herring crossed Europe and the sardine filled the cannery: it could be stopped from spoiling and carried somewhere it could never have swam to.

And for most of its history it carried no prestige at all. In the medieval kitchens of the Crown of Aragon, octopus and squid were filed under poor people's food, thought too tough and hard to digest for refined stomachs, fit for laboring bodies and little else. The elite cookbooks include them almost grudgingly. The cephalopod was the cheap, chewy thing the poor ate because the sea gave it away. Then, within living memory, the whole thing inverted. Tapas bars and sushi counters drove demand up, prices climbed, catches fell in the old strongholds of Spain and Japan, and Galicia now closes its octopus grounds for part of each year to let the animal recover while suppliers turn to imports. The poor man's mollusc became the prize people fly to Galicia to eat.

All of which is sitting, overlooked, in the strangest corner of the tinned fish aisle, and people walk past it for one reason: the cephalopod is the hardest seafood to cook well. Tough and rubbery if you undercook it, tough and rubbery if you overcook it, with a narrow window in between that home kitchens routinely miss. Which is exactly the argument for the tin. Galicia has been canning octopus for over a century and has the timing solved. A good tin hands you tender, properly cooked cephalopod that would take real skill to match at home. This is the rare category where the can is not the compromise. It is the path to the better result.

There are three doors in to this world. Octopus, or pulpo, is the gateway: a tin of it in olive oil makes pulpo a la gallega in under a minute. Open the tin, slice a warm boiled potato, pile the octopus on top, spoon over the oil from the tin, dust with smoked paprika. That is the whole dish, and it is genuinely good. Conservas de Cambados, Ramón Peña, and Ati Manel all make reliable tins. Squid and cuttlefish are the ones that scare people, which is a pity, because they are the most fun tins to open. Chipirones are baby squid, often whole and tender, essentially a ready-made pintxo. The dramatic version is en su tinta, in its own ink, a jet-black sauce of ink, tomato, and onion that looks alarming and tastes rich, briny, faintly sweet. Tip a tin over white rice, squeeze a lemon and watch the rice go black. Ramón Peña and Donostia Foods are good choices, and if the ink is a step too far, chipirones in plain oil are the more gentle way in.

The sardine and the tuna earned their place in the can by sheer abundance. The octopus earned it the hard way, dismissed for centuries, preserved by people who had nothing better, and in the end revealed to be one of the best things on the shelf. It is still the tin most people skip. It should be the one you reach for.

The strangest clam in the sea, smoked and sealed.

The geoduck is the largest burrowing clam in the world, and one of the longest-lived animals on earth: the typical lifespan runs to about 140 years, and the oldest on record passed 160. It does not look like a clam. Its two small shells cannot contain it, so a long fleshy siphon protrudes permanently, while the body sits buried up to a metre down in Pacific mud, the siphon alone reaching three feet. The Pacific Northwest, from Alaska to Baja, has eaten it for as long as anyone has lived there. Most of the world has never seen one.

Wildfish Cannery, working out of Klawock in southeast Alaska, is the rare house that puts it in a tin. The geoduck is cleaned, smoked, and sealed in a limited run that comes and goes. What you get is sweeter and firmer than a soft-shell clam, the texture closer to abalone or a good squid than to the steamers most people know, a clean woodsmoke note over deep marine sweetness. It is a tin you reach for when the usual sardines and mussels feel too familiar.

$22.99 at Caputo's.