Wesley, Angel and others in “I've Got You Under My Skin”

Wesley

You're thinking the demon's taken on corporeal form.

Angel

That's my guess. It can only absorb the elements it needs if it manifests itself physically which means if we can find it in time, we can kill it. He'll be looking for a hostile environment. Somewhere damp. Probably be turning to primordial volcanic basalt for his regeneration.

Cordelia

Huh?

Wesley

Sea caves.

Cordelia

Why didn't you just say that?