A Banksy mural, which recently appeared in the English coastal town of Folkestone is the latest of the illusive street artist’s works to be vandalized, the Independent reported. An unknown perpetrator painted a crude drawing of a penis to look as if it were sitting atop a previously-empty plinth.

Police opened a criminal investigation shortly after the damaged work was discovered. It has an estimated value of £300,000 ($480,000). A police spokesman told the Folkestone Herald: “Kent Police was called at 8pm on Sunday 12 October to a report of criminal damage in Rendezvous Street, Folkestone. It was reported an artwork on a wall had been painted on. Officers attended the scene and inquiries are ongoing.”

According to Kent Online, the vandalism has already been scraped off by specialists using a chemical removal treatment. The work is currently being protected by security personnel. Fortunately, Shepway District Council had taken the precaution of covering the mural with a transparent sheet plastic perspex, after it was discovered late last month. The method has been used to successfully preserve Banksy murals in other towns and cities.

Banksy confirmed that he had painted the artwork depicting an elderly woman looking at an empty plinth on September 29. The mural has helped to attract thousands of visitors to this year’s Folkestone Triennial. (see “Fresh Banksy Appears in Folkestone, England“)