The two spikes that the rover has recently found were formed likely as a result of similar processes. The SETI Institute took to Twitter to explain that these formations could be "the cemented fillings of ancient fractures in a sedimentary rock." Since the rest of the rock was made from a softer material, it got eroded over time and what we're seeing today is what was left.
Curiosity snapped a picture of the spikes on May 15th (Sol 3474) with the help of its Mastcam instrument. At the time, the rover was busy investigating the Gale Crater. More specifically, Curiosity was studying a region nicknamed by scientists Mirador Butte.
Last month, the rover had to climb the rugged terrain on Mount Sharp in order to get a better view of the complex bedrock. Using its Mastcam and the APXS (Alpha Particle X-Ray Spectrometer), it ran a chemical characterization of the bedrock and documented some of the interesting structures.
That includes the two spikes that look like petrified remnants of a tree. The rover has been investigating the Gale Crater's geology and environment, searching for signs of ancient microbial life. While these intriguing spikes are just rocks, they sure are an interesting find that shows what the conditions on Mars can create over billions of years.
#PPOD: Here is another cool rock at Gale crater on Mars! The spikes are most likely the cemented fillings of ancient fractures in a sedimentary rock. The rest of the rock was made of softer material and was eroded away. ????: @NASA @NASAJPL @Caltech #MSSS fredk, acquired on May 17. pic.twitter.com/RGfjmRBfI7— The SETI Institute (@SETIInstitute) May 26, 2022