Egg molds

This is probably a really stupid question...

Ok, so I just went to Chinatown NY and I jot my First ever bento box!!! But I also got an onigiri mold ( Though I really didn't need it:P) and an egg mold since I can't read Japanese... yet ... I don't know what kind of egg you're supposed to use, like a soft boiled one or a hard boiled one help!! Thanks a bunch maki-sama!!
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