A rare spider has been sent to a shop worker in Leicestershire.
The spider is often used in movies because of its appearance
The Mexican red-kneed tarantula, the type used in horror films, was sent in a box to the woman worker at Marks and Spencer at Fosse Park.
Staff called in the RSPCA to look after the potentially dangerous arachnid, which is an endangered species.
A man has been arrested in connection with the delivery on 28 March and released on police bail. The spider was recovered unharmed from the package.
An RSPCA spokesman said: "The police are investigating but it would appear this is a poison pen letter. It was a daft idea.
"They are not the most dangerous spider, but it could be fatal if it is given to someone who has an allergic reaction.
"The woman who received it must have been terrified. It was irresponsible of whoever sent it because they put whoever delivered it and the woman at risk, not to mention the spider."
The Mexican red-kneed tarantula can have a leg span measuring up to 10in, each of which ends with two claws which are used for tree-climbing.
It is said to rarely bite but flicks its hairs to blind and irritate victims.
A rare breed, it is the only tarantula on the Convention on Trade in Endangered Species (Cites) Appendix II list.