This work by an unidentified artist, "Commemorative head of a king (Oba)," Edo peoples, Benin kingdom, Nigeria (late 16th century), copper alloy, iron, 9 1/2 x 6 1/2 in (24.1 x 16.5 cm), is currently on view at the Museum of Fine Arts, Boston, but Nigeria wants it back. (image via mfa.org)