You probably haven't noticed this 'optical illusion' on your iPhone

With billions of iPhones sold, you might think we know everything about Apple's smartphone. But people are still just noticing a quirky 'optical illusion' in the phone's design. It's there on most iPhones since iPhone 7, but have you spotted it?

I think that describing it as an optical illusion is actually a little generous. It's basically just a redundant design feature that's used to make the phone look more symmetrical, but its still causing surprise (see our guide to the best iPhone 14 prices if you need to upgrade).

If you look at the bottom of your iPhone, you'll probably see two speaker grilles, one on either side of the charging port. But it's a design trick. Only the grille on the right side actually covers a speaker. The other one is mainly just for looks (you can try covering each grille as your play music to test it).

The extra grille isn't entirely obsolete in all iPhone designs, however. In recent iPhones, the holes nearest to the charging port in both grilles house the microphones that capture your voice when you're on a call.

For real optical illusions, see our pick of the best optical illusions of all time.