Some 900 years ago, a group of Londoners shared a communal toilet designed to fit three users at once. Now, Esther Addley reports for the Guardian, the unusually well-preserved plank of relief is set to go on view to the public for the first time, enabling visitors stopping by the Museum of London Docklands to delve into a little-discussed—yet ubiquitous—aspect of the human experience.

The 12th-century oak toilet seat will headline the museum’s upcoming Secret Rivers exhibition, which draws on archaeological artifacts, art, photography and film to “reveal stories of life by London’s rivers, streams and brooks, exploring why many of them were lost over time.”

The toilet once covered a cesspit that flowed into the city’s River Fleet, according to Brandon Specktor of Live Science. This drainage site, situated on what was then a small island, was likely used by occupants of a nearby commercial and residential building called Helle. As Addley notes, medieval records reveal a capmaker named John de Flete and his wife, Cassandra, owned the tenement.

“What I love about this is that we know the names of the people whose bottoms probably sat on [the seat],” exhibition curator Kate Sumnall tells the Guardian.

In an interview with the Press Association’s Sherna Noah, Sumnall explains that Helle boasted four ground-floor shops and a number of upper-floor rooms. Given the sheer size of the building it serviced, archaeologists believe members of the de Flete family weren't the only ones to make use of the plank.

Still, Noah writes, many of the details surrounding the three-seater loo remain hazy: It’s unclear whether men and women used the toilet at the same time, for example, and exactly how the carved plank managed to support the weight of simultaneous users. (Potential explanations posit the seat was held up by two tree trunks or belonged to a larger structure.)

“This [toilet] is a really rare survival,” Sumnall says to the Guardian. “We don’t have many of these in existence at all.”

A 12th Century communal, triple toilet seat, found in London, is going on display in May at the Museum of London Docklands pic.twitter.com/xV0VPFmmKC — Sherna Noah (@showbizsherna) February 13, 2019

According to Live Science’s Specktor, archaeologists first unearthed the toilet during a series of excavations conducted between the late 1980s and early 1990s. The Guardian’s Addley further explains that the dig, then the largest to ever take place in London, ran out of funding, leaving the seat hidden from public view for the next several decades.

Not only will visitors finally be able to examine the original 12th-century seat for themselves at Secret Rivers, but they will also have a chance to experience the cramped quarters of medieval bathrooms for themselves via a specially commissioned replica. As Sumnall tells Addley, the replica is actually quite comfortable—at least for one individual. Filling the seat to capacity, however, is sure to shift the experience considerably.

Secret Rivers is on view at Museum of London Docklands from May 24 through October October 27.