Last month, we found ourselves 50 people deep in line at Jurassic Quest, a three-day showing of animatronic T-rexes and triceratops at NRG Center. As our queue of strollers and wailing children slowly marched toward an area where kiddos could ride motorized dinosaurs, our attention was trained on a rectangle of Plexiglas affixed to the nearest wall, alongside a pair of support columns and a fire extinguisher. Beneath the clear plastic were three signatures scrawled directly on the beige concrete, one above the next. The names of Harris County Judge Ed Emmett and Gov. Greg Abbott were easy to identify, and unremarkable.

But we stood there transfixed by the top one, which is the reason this bit of graffiti has been clapped under protective screening: the totally illegible, yet immediately recognizable, signature of President Donald J. Trump, a man with a known affinity for large walls. Some say it resembles the Neiman Marcus logo, while one tweet memorably describes its aggressive angularity as “the sound wave of demons screaming.”

Unsurprisingly, people in line to see automated dinosaurs in a convention center packed with grade-schoolers shrugged dismissively when asked if they had any idea why our 45th president signed the western wall of Exhibit Hall E.

Turning elsewhere, we reached out to Toluse Olorunnipa, the Bloomberg News White House reporter whose tweet first documented the autograph back in September. Olorunnipa was tagging along on the president’s second survey of Harvey’s devastation—the same tour during which the leader of the free world bragged that his hands were too large for the provided latex gloves while serving meals at NRG Center—when he witnessed the moment. Trump had just finished visiting with children while photographers snapped away. Trailing behind as the press gaggle was shepherded to its next stop, Olorunnipa glanced back and saw Trump writing on the wall. Abbott and Emmett later followed suit.

Discovering the president spontaneously autographing a shelter housing thousands of hurricane victims was strange, but Olorunnipa says the incident was just “the beginning of a series of bizarre things that happened that day,” including the glove comment. “The president seemed to be enjoying himself a lot, which made it sort of surreal,” he says. “You’re visiting a disaster area—normally you expect presidents to take this somber tone.”

Olorunnipa doesn’t pretend to have an answer as to why Trump left his signature behind: “We can only just assume, based on the president liking to have his name on buildings, that this was another opportunity for him to leave his mark.”

A facility spokeswoman says there are no public plans for the wall, although, of course, “It’s no secret that it’s there.” And there it will remain, an unusually modest piece of Trump real estate blending into the background of auto shows and Jurassic Quests to come.