1 Break Thick Shells (Lobster And Crab) Into Smaller Pieces By Putting In A Sealed, Thick Plastic Bag And Either Rolling With A Rolling Pin Or Hitting With A Meat Hammer To Crush. Cut Up Thinner Shrimp Shells With A Chef'S Knife. Don'T Crush Or Cut Too Small. You Can Even Skip This Step If You Want, If You Are Already Dealing With Broken Up Shell Pieces (Like Cracked Crab). Place In A Large Roasting Pan And Roast At 400