As a defense mechanism, you build a shell.

For orchestral concerts there has been built a special acoustic shell.

Literally building a shell around their own sun.

She is a hard, brittle woman who has built a shell around herself, and reality won't intrude easily.

We could spot somebody building a shell around their star, or throwing in nuclear waste.

He was losing her as she built a shell around her heart to contain the pain.

Mathematically at least, it is possible to build such a shell without leaving the solar system for materials.

Instead he had watched her retreat into herself, building a shell against the outer world.

Coral is a very fragile animal that builds a shell around itself.

He had built a shell around himself, a love-proof box impervious to anything she had used to get through.