Monolith - A Space Odyssey (White)

Monolith from Arthur C Clarke's Odyssey series. The solid black one represents the humanity-era monoliths, like TMA-0 and TMA-1. The ones that appear during humanity’s development, are depicted as being more translucent, one of them is also responsible for Bowman’s transcendence. In the book it’s described as something you can partly see through, almost crystalline in nature.