Lidl is recalling packages of its Sol & Mar Squid in Sunflower Oil because of the appearance of small crystals, even though they don't pose a risk to health.
Two varieties of the squid - garlic and paprika - have been found to contain crystals of magnesium ammonium phosphate, generally known as struvite.
And while these crystals aren't poisonous, they can, says Lidl, be mistaken for glass and 'may cause injury' - although it's not clear how, as they certainly aren't sharp enough to cause any damage. They aren't poisonous, and if eaten, are broken down harmlessly by stomach acids.
Either way, Lidl is recalling both types of the squid, which come in packs of three and have a best before date of 31 December 2023.
Struvite often occurs in canned shrimp, tuna, salmon, and other seafood products, crystallising out of the mineral-rich contents. The crystals are, though, rarely big enough to be noticeable.
When they are, they can cause panic: when they were discovered in timns of seafood in the US during the First World War, it was for a while believed that ground glass had been added by enemy agents.
The same thing happened during World War II, and in 1942 the US government was forced to issue a news release to the public assuring them that the crystals were entirely natural.
"We are occasionally contacted after people find a piece of 'glass' in tinned fish, notably salmon, tuna, mackerel, shrimps, etc. This is actually a natural compound known as 'struvite' which is harmless," council food safety advice reads.
"Finding struvite is actually quite rare, despite the large volumes of fish produced each year. As yet, no procedure has been successful in preventing it happening, even the addition of polyphosphates is not 100% effective and most people do not want any more additives in food."
Customers who have one of the affected packs of squid can take the product into a store for a full refund, and can call 0370 444 1234 if they have any concerns.