An Oldblood House, Lineacrux, produced what might be thought of as archetypeal Great Houses - ponderous old men, serene and loath to take action. However, behind this facade they were ruthless manipulators and commited pursuers of what they considered the Homeworld's best interests. The House's robes were yellow, and typically shabby and aged.
During the War in Heaven, House Lineacrux was responsible for creating the Homworld's nine 'cloneworlds' using crypto-forming, although they prefered to allow other Houses to take the credit. (The Book of the War)