Guttae are irregularly shaped, relatively dark spots with bright annular features around them, known as Aureoles, that were seen by the Voyager spacecraft Smith et al. (1989) in the southern hemisphere of Neptune’s satellite Triton (Fig. 1). These features are about 50–80 km in diameter (Croft 1993). Bright plains with a number of topographic irregularities surround the guttae and aureoles. This topography extends and protrudes into the aureole materials, and in some cases into the guttae themselves, indicating that the plains units lay beneath these features. The smooth textures of both units are, however, distinct from the textures of surrounding plains units.