New photos from Mars from the Curiosity spacecraft may have shown evidence that an ocean once existed on Mars and was inhabited by living organisms. At least molluscs, whose shells can be seen quite well in the picture and which are different from the surrounding stones.
The shells are visible in two photographs taken on January 15, 2018, and lie very close to the rover's legs. Links to original NASA photos: photo 1, photo 2.
At first glance, it may seem that there are just two stones, but then you start to look closely and realize that on the surface of these “stones” there is a twist like shells, and both ends of each “stone” are narrowed, like shells.
By the way, this is not the first time objects that look like shells have been found in photographs from Mars. Below you can see the finds of "virtual archaeologists" from different years.
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