HARTFORD, Conn. -- When Koopa paints, he gets down and dirty. His feet are covered in all shades of blue and yellow and his slow-moving belly helps to form the abstract swirls that make up his art.

Koopa's paintings line her living room, turtle pillows crowd her sofas, and she has ceramic and plastic figurines of the reptile in nearly every corner. Koopa is free to roam around the apartment, ...