The “bubbles” seen by the Curiosity rover continue to be an interesting oddity. Another recent image from sol 137 shows a bunch of them on the bedrock, looking like tiny vents or really tiny volcanoes.
As seen in previous images, they seem to be in various stages of erosion, but generally have a conical or raised rim structure. The ones in this image appear to be more “filled in” while others seen previously were more like empty shells. Most of them also seem to be within one “swath” across the bedrock.
In appearance, they’ve been referred to as mud bubbles, vents, domes, rings, pimples and ant hills. Their origin is still being debated, but it will be interesting to see how many more are found in this area and in the surrounding terrain.