f(x)'s maknaes, Krystal and Sulli, looked pretty much the same since their childhood trainee days.

The photo titled, "Sulli and Krystal's trainee days", has been spreading online and proves that Krystal and Sulli are natural beauties even back in the day when they were still growing and didn't wear any makeup. 

Fans commented, "Sulli and Krystal are so cute", "So pretty", and "They have baby-like faces."

f(x), who are now all well into their 20s, are currently checking off their bucket lists on 'Amazing f(x)'.

Sulli and Krystal were always beautiful, but now they've matured into timeless beauties, wouldn't you say?