잠금 화면의 보물 상자는 뭐 하는 거야? 탭하면... 계산은 되는데 동전은 어디로 가는 거야?

Aly Pal!

It's part of the cash walk app. It all goes to your earnings when u tap it 

Kirisuki

The coins are used for gift cards for certain things but in my experience you need wifi or mobile data to collect them