These little dime-sized cactus in the photo are on the endangered species list.
They are called Brady's pincushion cactus (pediocactus bradyi). Common names also include Brady's hedgehog cactus and Marble Canyon cactus.
They only live at Marble Canyon and Vermillion Cliffs on windswept land.
These little cactus survive by the small rocks that provide cover and shade from the sunlight. The rocks also protect the cactus when people walk over and on them.
People unfortunately move the rocks to take photos or look at the cactus and then cause the cactus to get crushed or get sunburned and die.