The lyrics from Jay Chou's "Snail", this is an inspirational song, what is it based on?

This song by Jay Chou is an inspirational song. It is based on a (little snail) and is written in the first person (about the snail moving forward bravely and pursuing its dreams). This is also true. It is a portrayal of Jay Chou's own life.

There is a sentence in the song "A heavy shell is wrapped in a gentle look up. What is your understanding of this sentence (although its shell looks very heavy and inconvenient) , but even this heavy shell can protect the snail from wind and rain and help the snail continue to move forward).