Climate activists have been vandalizing art pieces to bring out their message of how conventional fuel badly affects the planet and, thus, its use should be stopped.

For maximum effect, the vandals target high-profile artworks. The famous Mona Lisa portrait at the Louvre Museum in Paris, France was splashed with soup early this year by two protesters who pretended to be visitors.

Fortunately, the soup did not damage the 1503 oil painting by Italian artist Leonardo da Vinci as it’s protected by a bulletproof glass barrier.

Meanwhile, another suspected painting vandal is being investigated by police in Andalucia, Spain.

The man, identified only as a 39-year-old resident of Los Villares, visited one prehistoric rock art site in the area in May. He took photos of 6,000-year-old cave paintings in the Sierra Sur of Jaén and posted the images on social media.

Authorities noticed in the photos that the cave paintings were wet and suspected that he had violated Spanish heritage law.

Cave paintings in that region were mostly made on limestone, which contains water soluble salts. The suspected vandal allegedly poured water on the rock paintings which dissolved the salt, “creating a pale crust over the top of the paintings,” Artnet.com reports.

The man then doused the paintings to make them clearer for photos he wanted to share on Facebook, according to Artnet.com.