Right, surely the icons could be SVGs, with the background orbs stored as a base64 PNG (or maybe a specular lighting filter?), with the foreground icons made to move via an updating displacement map?
Even if they didn't want to go that route, What I've seen google do in the past is render every frame to a texture atlas, and write a CSS animation which updates the background-position property at 60 frames a second, so at least you don't have to load 150 images at a time