gently take that shell off... some tiny tweezers from an old swiss army knife is what i've used before.. along with a toothpick. sometimes a little membrane remains wrapped around the cotyledons after you remove shell... try to slide it off, don't try to rip it apart. get toothpick in between leaves and gently push/slide the membrane off.
the shell you sometimes have to pry it open a bit more before gently removing it. try to put as little stress on the stem and plant as possible.
ripping of 1 coty is bad, but it will survive. it will be set back a bit. if the growth tip is damaged just toss it. it'll be forever before it grows a new one or might just die.