I agree. That bone-like, fossil-like feature in the center is very interesting. I wish the image was in color! Earthly fossils often have a distinctly different color than what they are embedded in. I wonder if this is the case here.
They've already concluded that there was probably water in abundance on Mars...perhaps lakes, streams, maybe even oceans. Water is the main ingredient for life.... to think that this may be a fossil is not a stretch in the least. What I can't understand is why mainstream science won't at least discuss it.