It’s not stock. It’s Shutterstock.
I saw a Dribbble shot the other day by Eli Brumley that had a cool interactive effect. A simple circular blue button, when clicked, expands into a small menu itself. I fired up Professor Mode on CodePen to let people watch as I built, but I also recorded it so I could talk my way through it and publish it here.
See the Pen Menu Toggle Thing by Chris Coyier (@chriscoyier) on CodePen.