Marl

Marl is an earth elemental known as a Galeb Duhr, an intelligent creature with the power to animate stone and earth. They look after and create the elementals in the top cavern under Beacon, and carved the gargoyles and the cobbles with the help of their xorn.
Claims to have been imprisoned for a time even deeper, and burrowed upwards before settling in the uppermost cavern. Spent many years slowly eating the inanimate constructs, but their children are now under threat as the constructs have awoken. 
Extremely nervous, worried about their future, and unsure how to socialise, but seems to be genuine.