Crags Magnetic Putty
These ferrite magnetic stones are like putty in your hands. At least if the name "Crags Magnetic Putty" is to be believed. A cross between silly putty and Micromagnets, this "oddly satisfying" fidget toy consists of over 500 jet black magnets of varying oblong shapes that flow around and through each other, as well as cascade in slo-mo down toward their magnetic base.
En masse, the Crags Magnetic Putty stones look like a bowl of buffed lava rocks, or maybe carpenter ants, but my sense from the video is that they feel much smoother and more tactilely pleasing. Probably won't provide much exfoliation like the lava rocks, or make your Aunt Jan cry like the ants though.