Actually, calling it a "weird rock" kinda misses the point of it being in VR. Since it's not a real, physical object, you're really adding a digital sculpture or a 3D model. The cool part is that it only exists as code and light, which makes it way more flexible than an actual rock. You can make it float, glow, or change shape whenever you want. Calling it just a rock downplays what you're actually building in that space. It's a whole different kind of art when the material isn't physical at all.
My friend tried making a vase in VR last year and kept getting mad it didn't look like real clay. He finally gave up on that and made the whole thing spin and drip little stars instead, which was way cooler (and something you could never do with actual pottery). It totally changed how he saw the stuff you make in there. Now he just plays with what the program lets him do, not what a real object should be.