The structure was discovered on Thursday by Toronto resident Mon Lerin along the edge of the Humber Bay Trail.
"It was not there yesterday morning since I go every day for morning walks," said Lerin to Narcity.
Earlier this month, a Winnipeg local spotted a similar monolith, however, it didn't take long for the structure to suddenly disappear.
"Not sure if it was parks officials or aliens," he tweeted.
Days later, photos of a large monolith in Lethbridge, Alberta were shared on social media.
The monolith saga began with two sightings in the Utah desert, followed by another one on a Romanian hillside.
One was also found in the city of Ahmedabad in India today, according to India Today. The mysterious rectangle also features symbols and numbers on its surface.