David Beckham has been pictured eating a rather unusual-looking delicacy.

The former footballer posted snaps on his Instagram stories of morsels that admittedly look rather alien-like.

These are percebes – what Beckham calls “one of my favourite things to eat when in season” in Spain. And it would seem like Beckham knows what he’s talking about – in the recent Netflix documentary tracking his life and career, he was revealed as a keen cook and foodie.

Percebes go by many names – including goose barnacles, leaf barnacles and even Lucifer’s fingers. They’re strange in appearance, with a dark, rubbery stem and a white head that looks a bit like a goose’s beak.

They look interplanetary, but are actually a rare type of crustacean. They’re notoriously difficult to source: percebes are chipped off rocks in often dangerous coastal spots along the western European Atlantic coast – the Costa da Morte (Coast of Death) in Galicia, Spain, is a famous hotspot for harvesting the barnacles.

Harvesting percebes often involve scaling dangerous cliff faces, getting buffeted by waves and even going underwater. This means they’re relatively expensive – and the bigger the barnacle, the more money they’ll fetch, as they contain more meat.

Percebes are most common in Spain and Portugal – particularly around the seaside areas where they’re harvested. According to The Fish Society, one 250g pack – which contains around 10-30 barnacles – will set you back £24.50.

“A large barnacle is usually about seven centimetres long,” The Fish Society says.

If you’re cooking percebes at home, the process is simple – all you have to do is boil them in salted water for a few minutes and they’re good to go. Most recipes suggest keeping things simple – eating them as is, squeezing over some lemon, or garnishing with herbs like parsley.

The flavour is apparently incredibly salty – percebes are said to be basically the closest things you can get to tasting the sea – while also being like a cross between lobsters and clams.

To eat the alien-like barnacles, you squeeze the hard shell to make the flesh come out.

If you do decide to splash out and try these strange delicacies at home, be warned – The Fish Society says: “We should tell you that you will get a certain amount of genuine rock (as in, the cliff) in your pack because the barnacles are very firmly attached to it and would be damaged if removed before cooking.”