Making new friends helped her 'come out of her shell'. = Making new friends 'brought her out of her shell'.
He lost confidence in himself and 'retreated/withdrew into his shell'.
The police found several spent 'shells' at the scene of the shooting.
(..) East Australian Current. EAC? Dude... You're riding it, dude. Check it out. Okay, grab shell, dude. Grab what? Grab what? Righteous! So... what brings you on this fine day (..)2003 Finding Nemo
(..) - What are you talking about? You, mini-man! Taking on the jellies. You got serious thrill issues, dude. Awesome. Oh, my stomach. Man, no hurling on the shell. l just waxed it. - So, Mr Turtle... - Dude, Mr Turtle is my father. Name's Crush. Crush? Really? (..)2003 Finding Nemo