One day, when nature calls, your urine could be put to better use than to be flushed down the loo.
Instead it could be a key ingredient in the construction of a greener office or new home.
In one of the latest innovations in the search for eco-friendly building materials, South African university researchers have created bricks using human urine.
The first of their kind in the world, the bio-bricks hold out the prospect of a sustainable alternative to standard clay and concrete bricks, they hope.
The prototypes have been "grown" from urine using a technique somewhat similar to the natural formation of seashells, taking six to eight days to form.
The groundbreaking invention is the brainchild of two University of Cape Town students and a lecturer.
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With a grant from a government-run Water Research Council, the feasibility study was launched last year using synthetic urea.
And then the study escalated to using human urine.
"I was always curious to know why don't we use urine to do the same thing," Dyllon Randall, the lecturer who supervised one of the two students, told AFP.
"The simple answer is: 'Yes, we can'."
"This process is amazing because essentially what we've done is we grew bricks at room temperature."