Hook: Floor Large (Purple Square)The Adolescent Thranta Skull decoration fits into a large purple square floor hook.
How to Get an Adolescent Thranta Skull Decoration
Cartel Pack Decorations
The Adolescent Thranta Skull decoration can be dropped from Discord PacksUltimate Cartel Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Discord PackUltimate Cartel Pack, include a random selection of items from the Discord Ultimate Cartel collection of items. You aren't guaranteed to get an Adolescent Thranta Skull decoration from a Discord PackUltimate Cartel Pack, but it is one of the few ways to get an Adolescent Thranta Skull deco apart from buying it on the GTN from another player.
If you're looking to get a Adolescent Thranta Skull, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.