For years, scientists believed that the colorful deposits found in lava caves around the world were mineral deposits, but more recently they've discovered that the collections — ranging from blue-green drips to shimmering pink hexagons — are actually microbe poop.

At a recent meeting of the Geological Society of America, researchers announced that the colorful deposits, found in lava caves all over the world, are in fact biological in origin. Previously undetected microbes excrete waste inside the caves and the buildup of what one geomicrobiologist terms "bug poop" creates these impressive displays.

This discovery — that something long thought to be mineral turned out to be biological — has implications for researchers looking for life on Mars. Based on photos of the surface, it appears that Mars holds, or at one time held, lava caves similar to those where the microbe waste was found, and similar microbes might have thrived inside those caves. Mars researchers may want to consider taking samples of apparent mineral deposits to determine if those deposits are, in fact, "bug poop."

Lava Cave Minerals Actually Microbe Poop [National Geographic via Neatorama]