large marine arthropod of the Atlantic coast of North America having a domed carapace that is shaped like a horseshoe and a stiff pointed tail; a living fossil related to the wood louse 
                                                            
                                                     
                        
                                                
                        
                        
                            A player whose hole cards consist of a King and a 3. 3's are commonly called crabs because of the slight resemblance.
                                                            
                                                     
                        
                                                
                        
                        
                            King (K), three (3). so called because the 3 resembles a crab.