Every ghost shell I have (I've got about 8 or 9 across all of my characters) has either a material sensor perk or a material extractor perk. I have some for wormspore, some for spirit bloom, some for relic iron, and one for spinmetal. I do not however have one for helium filaments. I've been looking at vendors, examining every ghost shell I get, looking for one that does anything related to helium filaments. For some reason, despite looking for over a week, nothing has shown up. Do helium filament ghost shells exist? If so, how do I get one?