Corruption Grass

The Corruption Grass (as the name says) appears in the Corruption. As [grass] it can grow on dirt but it can also corrupt the Grass block itself!

Trivia

 * The graphic was first a mix of purple and pink and is now more blue-ish.
 * In the very early states of Terracraft you could/can make a Meteorite spawn by hitting the Corruption Grass with right click.