Asda have said they do not know how a yellow piece of rubber found its way into a customer's rogan josh sauce.
Donnalyn Harrison, from Washingborough, found the object after using a jar of sauce to make a curry for herself and her husband.
She said: "I had everything in the wok and picked the jar from the cupboard to pour the sauce out. I served it out on the plate to my husband and he just turned to me and said 'what the bloody hell is this?'
"The piece of rubber we found looked like it could have been a handle or a stopper of some kind. It had a nodule so obviously fit into something.
"But it was no bigger than a 10p coin, so if one of us had swallowed it, it could have trapped our airways."
The piece of rubber was sent to Asda and a full investigation carried out, but it has been determined that it was "not present" during the manufacturing process.
A spokesman added: "We can only apologise for any inconvenience caused.
"Our store colleagues offered the customer a full refund and gesture of goodwill and our customer service teams has been in contact with her to keep them up to date with the investigation."