Please go to the category: "Shoes" for more information and URL to Curiosity Rover photos. Please pay careful attention to the second photo and within the yellow rectangle are what looks like a
long roller with fish type creatures seemingly being flattened by rollers. Also notice who the 1st photo has a process that looks like there are "rollers" too for flattening creatures. But it is subtle and if you don't look close you will miss it!