There’s this one storyline in TCW about this gargantuan creature that had indestructible skin, so much so that even lightsabers bounced off it. After killing it Palpatine commissions a secret cloning of the creature to research its skin impregnable properties.
What bothers me is that this story is never brought up again. Don’t know if there was a Legends continuity comic or something that wrapped up the story, but under the Disney canon the story remains unresolved.