In Super Smash Bros: Melee, Yoshi uses his egg as a shield instead of the normal shield that other players use.
Functionally, what is special about this egg as compared to the normal shield?
I've found these references on the Melee wiki (emphases mine):
Yoshi has a different shield from that of other characters'. Instead of using a bubble, he uses an egg for protection. This egg does not shrink, preventing any attempts at shield stabbing.
Also, Yoshi has been known to randomly perfect shield (not completely understood, but may have something to do with the egg remaining full size), and is also invincible during his shielding animation.
Are the only unique characteristics of Yoshi's egg shield that the egg prevents shield-stabbing, and can randomly perfect shield? If so, is there more information on this random perfect shielding phenomenon? If not, what else is unique about Yoshi's egg shield?