The symbol that looks like a snowflake under the note is the "pedal symbol", often called the "pedal mark" or "sustain pedal mark". It is a mark when the pedal is pressed, usually appearing on In piano sheet music.

This symbol means that after pressing the pedal on this note, the sound will continue to the next note, making the sound longer. This symbol usually appears on the last note of a bar or chord, indicating that when the pedal is pressed on this note, the sound will continue until the first note of the next bar or chord.

It should be noted that this symbol is just a mark, and the actual pedal use needs to be judged and adjusted according to the feel and style of the music.