What is the Renzo protocol Eigen?

Could you please explain to me what the Renzo protocol Eigen actually is? I've heard about it but I'm still not entirely clear on its functionality and purpose within the realm of cryptocurrency and finance. Could you provide a concise yet informative description of Eigen, highlighting its key features and how it contributes to the overall Renzo protocol? I'm particularly interested in understanding how it works, its potential benefits, and any challenges or limitations it might have. Thank you for your assistance in clarifying this topic for me.