"Look, it's alive," says the restaurant greeter as he taps the wobbly tip of an obscene-looking razor clam known as a lingueirão, causing it to retreat into its long, skinny shell.
In a vast glass cabinet filled with marine animals of all shapes, sizes, colours, and degrees of being alive, this one is arguably the least appealing to the eye.
But in Sesimbra, a sedate seaside town at the foot of the Arrabida mountain range in Portugal, every restaurant window attempts to outdo its neighbour in the weirdness of seafood on offer. The array of slippery fish, giant egg sacks, jelly-like squid, and knobbly crustaceans is not for the gastronomically timid. Some of the creatures are snappingly alive, others are dead. With the shellfish, it's pretty hard to tell.
This is especially true of the lingueirão. While the enormous eel, staring up at me with its glassy eyes, is definitely dead and the percebes are unmoving, the razor clam remains ambiguous.
The way to tell if the longueirão, also known as navalhas or canivetes, is fit to cook is by poking it. If it doesn't promptly withdraw into its shell on contact, this means it's either dead or dying.
The clam's body is largely made up of a foot, which is hydraulically inflated and used to propel it beneath the sand, with the creature squirting water to clear a path as it goes. Once it reaches a safe depth, the clam anchors its inflated foot in the sand, before deflating it to draw down its protective shell.
Longueirão is traditionally used in the rice dish arroz de lingueirao or blanched with olive oil, coriander, lime, and white wine to make the appetiser lingueirão à bulhão pato.
Fascinated by the clams, I'm put in touch with a local who catches longueirão for a living. Senhor Jaime camps out in a beach hut at Lagoa de Albufeira, a nearby beauty spot where a beach-ringed lake is separated from the Atlantic ocean by a thin strip of sand.
It's the winter low season and when I arrive at the lake, I see wooden platforms topped with small clapboard huts floating unattended, silently gathering mussels on the ropes that hang into the water. I find Jaime at a nearby seafood restaurant, smoking a cigarette after dropping off his haul of fresh seafood.
Sitting down to tell me about the fate of the lingueirão, he orders coffee with a generous dose of dark rum.
"This used to be a good place to catch them but not now," he says. "They are gone from the lake. Now you need to go to Setubal but there are less of them there too."
Setubal is a peninsula some 20 kilometres south of Sesimbra, known for its dolphin-watching opportunities. Jaime explains that the fishermen catching razor clams by hand have been outdone by trawlers that rake the sands mechanically, overfishing the lingueirão to the extent that they have been all but wiped out locally.
But today, Jaime says, it's all about mussels and eels.
"Everybody that comes to the Lagoa wants to eat eels," he says and to illustrate this point, he asks the restaurant's owner to bring one over. It lies there, staring up at us for the remainder of our conversation. "Eighty percent of the people that come to the restaurants here want eel."
The eels' most popular guises are ensopada (a kind of soup) or stewed with potato, garlic, onions, and parsley to make caldeirada. Mussels are big business too, and Jaime points to his platform out in the waters, where the shellfish grow until they are ready to be harvested.
But as we survey the colorful contents of the local restaurants' glass displays, Jaime laments the missing lingueirão.
"They're still common in the restaurants in Sesimbra but they have to bring it in from farther and farther away," he explains. "It's illegal to fish for it in certain areas and at certain times of year, but people still do."
We see eel, oysters, stone crab, spiny santola, and the sapateira crabs that the locals like to serve with roe, hens' eggs, and mayonnaise mixed together and stuffed into the stomach cavity. But the razor clam is conspicuous by its absence.
"Not one lingueirão to be seen," says Jaime.