[SPOILER] Which 'Produce' series idol wowed with their unique vocals on 'Mask King' this week?

On the December 9 episode of the MBC singing competition 'Mask King,' four new contestants battled for a chance to overthrow the latest king 'Eagle'!

During one battle, contestants 'Icicle' and 'The First Snow of the Season' performed a duet for the audience, singing Baek Ye Rin's "Across The Universe" and exciting the panel with their clear, flawless vocals. The audience vote revealed that 'The First Snow of the Season' beat 'Icicle,' meaning 'Icicle' had to drop out of the competition and reveal her identity. 

'Icicle' proved to be none other than 'Produce 48' project group IZ*ONE's Ahn Yu Jin, who immediately went into a cover of Heize's "You, Clouds, Rain." During the reveal interview, the panelists praised her performance and complimented her vocals, calling them "beautifully unique." They were also quite stunned to find that the singer, who was born in 2003, had so much vocal talent at just 16 years old.

Check out Ahn Yu Jin's full reveal stage below!