GRAND RAPIDS, Mich. -  Chicago art conservator Barry Bauman discovered a hidden image of a butchered pig in a 17th century Dutch painting from the collection of Michigan's Calvin College. While he cleaned "Barn Interior" by Egbert van der Poel (1621-1664), the scene of a woman and two children brightened and also revealed the gruesome picture of the piggy strung upside down from a ladder. A patron may have had the piggy painted over. The discovery led to another find: Barn Interior's "pendant," or companion painting, hangs in the Rijksmuseum.