Stein initially threw the pack away after noticing that the mass was twitching, but later retrieved the fruit to examine it further.
“Opened the bag, everything fine, turned the bananas over and all I saw was this huge dark mass hanging on to the bananas,” he recalled.
“It was a spider and it started to move so I shouted to my girlfriend ‘don’t come in the kitchen’.”
After taking a closer look at the spider and researching its features online, Stein believes it may have been a Brazilian wandering spider. Its scientific name, Phoneutria, translate as “murderess” in Greek.
Like the wandering spider, the one in Stein’s bananas had a body length of around two inches and was covered in brown hair.
“I emptied the whole bag into a plastic box, and as soon as it fell out I put lid on it and I could tell it wasn’t moving. We Googled it and it looks 99 per cent like the wandering spider,” Stein said.
“I saw a few pictures, it looked identical; the big hairy legs, the big abdomen with the little humps coming out and a black line.
“I was a bit shocked to find out it’s one of the most venomous and dangerous spiders in the world.”
According to Buglife, an insect conservation organisation based in Europe, a bite from a Brazilian spider can produce intense pain, visual disturbances, salivation and profuse sweating.
Stein bought the pack of bananas, which had been grown in Colombia, at a Sainsbury’s branch in West Wickham.
“I want to make people aware to be careful,” he said.
The spider has now been sent to Sainsbury’s for further investigation.
A Sainsbury’s spokesperson said: “We’re in touch with the customer to apologise for their experience.
“Incidents like this are extremely rare and we have processes in place to prevent them.”