(CNN)Police are investigating after a customer at a Primark store in Essex, UK, got more than they bargained for after buying a new pair of socks.
An unhappy shopper made the grisly discovery of what is believed to be part of a human bone, said officers.
"The bone does not appear to be a result of recent trauma and had no skin or other particles surrounding it," Essex Police said in a statement.
It added that the item was bought at a Primark store in Colchester on December 10 and the discovery was reported on January 2.
Officers have been working with the store to find out more about the incident, and the company has issued an apology.
"Primark sincerely apologizes to the customer who found the item for any distress caused," a spokesperson said.
"Primark clearly takes this matter very seriously and has already carried out an investigation at our supplier's factory where the socks were made," they added.
They said there was "no evidence of any kind" to suggest that an incident that would explain the discovery took place in the factory.
So, they said, the company believes it is "highly probable" that the unusual object was "placed in the socks by an individual for unknown reasons."
The spokesperson added: "Primark has been the subject of isolated incidents in the past which have subsequently been found to have been hoaxes."
In 2014, however, a customer in Northern Ireland reportedly discovered a chilling note stuffed in a pair of pants she bought from the clothing chain.
Scrawled on a yellow piece of paper and wrapped around what appears to be a prison identification card was a message claiming to be from an inmate at a Chinese prison making clothes for export under conditions of slave labor.
"We work 15 hours every day and eat food that wouldn't even be fed to pigs and dogs. We're (forced to) work like oxen," the handwritten note said in Chinese.
The message appealed to the international community to "condemn these human rights abuses by the Chinese government."
In a statement issued at the time, Primark denied sourcing clothing made using forced labor.