As someone who believes that life once existed on mars (And still could) I am delighted with further evidence comes along to support this. The image below just came in from Curiosity's MAHLI cam, it's a close-up shot of a rock showing features that - at least to me - are reminiscent of fossilized biological life forms. Here's an animated GIF highlighting the more noteworthy shapes and streaks: These features (especially the whirly thin tube) instantly reminded me of algae: Grypania spiralis was an early form of algae on Earth, here some fossilized remains (for comparison): Grypania Spiralis Grypania is an early, tube-shaped fossil from the Proterozoic eon. The organism could have been a giant bacterium or bacterial colony, but because of its size (over one centimeter) and consistent form, is more likely to have been a eukaryotic alga. The oldest probable Grypania fossils date to about 2.1 billion years ago and the youngest extended into the Mesoproterozoic era. Yet another biological explanation could be that these are "trace fossils" left behind by organisms making their way through the ancient soil, here's an example (from Earth): Personally, I think these images are unique and I can't remember having seen anything comparable in previous MAHLI images. The twisting and whirling form of these tubes are quite remarkable IMO and the exciting thing is that it's not a single isolated feature but a great many of them on this particular rock (including additional shapes that somehow resemble other primitive organisms known from terrestrial fossils).