Butterfly vent
Butterfly vent This color view of Mercury's surface highlights what may be an old volcanic vent. Just to the right of center, within a brown-red patch, is an irregularly shaped 30-km depression depression, in this case the irregular shape is a bit like a butterfly. While most of these suspected volcanic vents are located within impact craters (like this one), the butterfly-shaped vent is not clearly associated with any crater. It also appears that it may be older than other vents, resulting in more subdued details and colors. NASA / JHUAPL / CIW