These Victorian optical illusion postcards are freaking me out

Optical illusions often walk the line between cool and creepy – there's nothing quite like having the deceptiveness of our own brains pointed out to make us start questioning everything. But they get even weirder with the addition of some good old uncanny Victorian photography. And some skulls thrown in for good measure.

Yep, some Victorian era postcards have recently gone viral on Instagram, and they demonstrate how the public penchant for illusions long predates the internet. We've seen vintage skull-based optical illusions before, but these might be the creepiest yet. There's just something unsettling about Victorian children. 

"Optical illusion skull postcards were incredibly popular in the early 1900s in Europe," explains the popular @GotWeird account. "They were Vanitas or Memento Mori - Intended to cause the viewer to reflect on the inevitability of mortality and the consequent foolishness of all human ambition." And, yeah, these are certainly making me reflect on the inevitability of mortality more than that rotating horse ever did.

From penguins in space to floating planes, we've seen all manner of weird and wonderful optical illusions recently. For some of the best examples in one place, check out the best optical illusions of all time.