The Keyhole Nebula . ... Credit Copyright: NOAO , NSF ; Copyright: AURA Explanation: The dark dusty Keyhole Nebula gets its name from its unusual shape. Officially designated NGC 3324, the Keyhole Nebula is a smaller region superposed on the larger Eta Carina Nebula . ... Noted and discussed as early as 1840 when a spectacular explosion became visible, the Eta Carina system now appears to be undergoing an unusual period of change . ... NASA Web Site Statements, Warnings, and Disclaimers . ...