Not quite immune - it melted a bit, hence why bomb material got mixed into it and needed to be capped with something to make it safe. Fortunately the 'wave likes disposing of hazardous material. As for what precisely it is... before being waved, asteroidal Ni/Fe, while the seibertron wave was working similar alloying and crystallization patterns to steel were observed... it's like Captain America's shield. More directly, it's the feet thick wavesteel to that hair thin layer of wavepaint that makes your car
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"Anko, what you do in your free time is your own choice. Use it wisely. And if you do not use it wisely, make sure you thoroughly enjoy whatever unwise thing you are doing." - HymnOfRagnorok as Orochimaru at SpaceBattles
woot Med. Eng., verb, 1st & 3rd pers. prsnt. sg. know, knows
--
"Anko, what you do in your free time is your own choice. Use it wisely. And if you do not use it wisely, make sure you thoroughly enjoy whatever unwise thing you are doing." - HymnOfRagnorok as Orochimaru at SpaceBattles
woot Med. Eng., verb, 1st & 3rd pers. prsnt. sg. know, knows