Can lobsters grow new legs?

Yes this is called of reflex amputation (autotomy). They can discard a limb, this can be a lifesaving phenomenon. Lobsters have the ability to regenerate some of their body parts, for example, the claws, walking legs, and antennae. the fact that lobsters are capable of limb loss and regeneration is indicative of a very primitive nervous system and their differential sensitivity to pain compared to humans or other types of animals (they can "drop" a claw, etc. and go off like nothing happened. Could you drop an arm or leg like that?).