The 55th Alphic Hydras are one of the most well-respected Militarum Tempestus regiments in the Imperium. This is in part because of the number of missions that they have fought alongside the Ultramarines -- to date they have made planetfall alongside the 2nd, 5th, 7th and 8th companies over their illustrious career. So close is the association between these Scions and the Space Marines that the Alphic Hydras have recently been permitted additional training grounds throughout the Ultramar system. Some within the Ordo Tempestus whisper that some of the regiment's best young Scions have even been recruited by the Adeptus Astartes.