If the tunnel is empty, or if what's in it is simple, sturdy stuff, there might not be any harm.

Apparently Thallonians were made of fairly sturdy stuff; the disruptor shot would have killed most others.

But when it's young, it's actually rather sturdy stuff.

Our founder has never quite reconciled herself to iron, but it's sturdy stuff and the spell should be good for at least twenty-four hours.

The good part about the apartment was that it had been built with sturdy stuff.

Men must be made of sturdy stuff to keep trying in the face of adversity brought on by both nature and other men.

"Perhaps they're making humans of less sturdy stuff nowadays."

In fact, wine is sturdier stuff than it might seem to be.

The furniture was all antique; sturdy stuff that had been handmade by local craftspeople.

But no, it simply banged and rattled to a stop-evidently those boards were made of sturdy stuff.