Why had his heart chosen this moment to break through its protective shell?

Instead she felt the draw of a presence just outside the protective shell, something that was close but oddly far away.

But the parents know this protective shell is thin armor.

Peter enters a protective shell to shield himself from the changes.

All we can do is be here when he decides to pull out of his protective shell.

But once inside their protective shells, some simply laugh off any attempt to deal with them.

But once it was over, they withdrew into their own protective shells again.

Modern car finishes form a protective shell around the paint job.

He subconsciously knew that I had set a protective shell around myself.

These eggs have a protective shell, and are laid out of water.