The party encountered the Urruk scorpion while they were searching some lost archaelogists, the Gargantuan (as in D&D sizes, meaning way larger than an Elephant) scorpion sand glided to the party and attacked them with their giant stinger and claws.
That was the first creature who benefitted from Gargantuan creature damage reduction (and by now the only creature that benefitted from that, the only other things that would have benefitted from that size-wise worked under different rulesets.) Meaning that if you hit the creature (multiple attacks do count) and don't do 16 or more damage, the creature would instead don't gain any damage at all. Even if you would do more than 16, all damage would then be reduced by 8. Simulating that creatures who are just very very big don't care about little pinprick arrows or a little cutting from a small human. Weapons must be hold in a truly heroic fashion to harm creatures like that.
Apparently scorpion flesh is quite delicious. Angel could mine for two doses of BRUTAL Con-poison, most likely Marp's armour was created from armor plates of a scorpion like that.
Del's group of orcs apparently were also able to kill a Scorpion like that.