Washingtonian first noted on Tuesday that Zuckerberg’s chair was outfitted with a thick extra cushion, which was reportedly supplied to him by Congress. The internet quickly latched on, cracking plenty of jokes about the “billionaire’s booster seat.”

Mark Zuckerberg in a booster seat looks like he’s about to ask the waitress for chicken fingers and apple juice pic.twitter.com/oGA6RkGE4S

— Jules (@Julian_Epp) April 11, 2018

https://twitter.com/MarkDice/status/983809841549393920

https://twitter.com/MeanwhileScotia/status/983814592278224896

While many have suggested that Zuckerberg — who, depending on which source you cite, stands around either 5’7″ or 5’8″ — used the cushion to appear taller, it may actually have served a legitimate purpose, says Dr. Joel Press, physiatrist-in-chief at the Hospital for Special Surgery in New York City.

“It’s not crazy. As a matter of fact, a lot of people in this country…use a little back support,” Press says. “There’s probably some reason for it, whether it’s related to back- or hip-related things.”

Press says sitting for extended periods can put strain on the discs in the back, more so even than walking, standing, or moving around. As such, many people use cushions that offer elevation or extra support to specific areas of the back. Cushions may also be used for injuries to the hamstrings, hips, thighs or buttocks, Press says.

Press adds it may be uncomfortable for shorter people to sit in some chairs, since they’re typically made with a person between 5’8″ and 5’10” in mind. (He adds, however, that Zuckerberg “doesn’t seem like he’s got to be sitting up higher.”)

All in all, Press says that, while an extra cushion likely isn’t necessary for your day-to-day sitting needs, “We do recommend the average person, during their work day, have some support while they’re sitting. You want people with good posture when they’re sitting as much as possible.”