A man who opened a parcel addressed to his new home was horrified to discover a large and potentially aggressive tarantula inside.
The householder received the Brazilian Salmon Pink Birdeater - the third largest spider in the world - in a "Return to Sender" package intended for the previous owner of his property in Bristol.
Dates on the parcel showed it had been unopened for about three weeks and the tissue bedding in the tarantula's container had gone mouldy.
The man took the spider to Highcroft Veterinary Group in Whitchurch, Bristol, where it was examined and found to be "very unwell".
Vets confirmed the spider as a Brazilian Salmon Pink Birdeater, which can grow to have a leg span of 11in (28cm) and are known to be semi-aggressive.
The species, with 1in (2.5cm) fangs, are capable of "kicking" hairs from their abdomen as a defence mechanism, which can be a skin irritant and cause blindness.
Sonya Miles, a veterinary surgeon at Highcroft, said: "When I examined the tarantula it was clear it was very unwell, as it was showing signs of dehydration and had lost a lot of hair from the abdomen.
"Mould can affect tarantulas very negatively so, with the exposure to the fungus and being stressed after circulating in the post for so long, I'm surprised it even survived.
"It is common to send insects and some living creatures via the post, as long as they are clearly labelled in accordance with the postal service being used.
"Although the package did adhere to all the regulations, it was just an unlucky situation that resulted in it not being collected by its intended owners."
Miss Miles took the spider, which she has named Sid, to recuperate at her rescue centre, North Somerset Reptile Rescue.
She hopes it will find a new home once it has calmed down and can be handled.
Highcroft Veterinary Group owner Richard Killen said: "I am delighted we were able to treat this significant species of spider.
"We are one of the few veterinary practices in the South West that has the level of expertise to know how to deal with such an unusual pet.
"We are very proud to be able treat all kinds of companion animals - from cats and dogs right through to the most exotic of species."