It was as if she offered him something warm, soft and sensitive, yet the moment he reached out and touched it, she shot back into her hard, impenetrable shell.

Cannoli, on the other hand, had coarse, impenetrable shells and a too-sweet ricotta filling dotted with tiny chocolate chips.

In moments the dome was an impenetrable shell once more.

It seemed as if the reactor was at the exact center of an impenetrable, spherical shell.

Serrano's face seemed to close into an impenetrable shell.

Otherwise, a small explosive device could be set off within a starship's shields, with the full force of its blast reflected back toward the ship by an impenetrable shell of energy.

I want an impenetrable protective shell around them.

The Enterprise was, according to the sensors, surrounded by an impenetrable cube-shaped shell.

To be avoided: tourteaux, crabs with nearly impenetrable shells.

The extra weight that the actor has packed on gives him an air of vulnerability that makes his character's ultimate emergence from his seemingly impenetrable emotional shell all the more moving".