Tale of a mermaid.

Sirenomelia is a rare congenital anomaly characterized by the presence of a median single lower appendage. The affected fetus is popularly referred to as a "Mermaid baby," due to the uncanny resemblance to the fictious fable character. The manifestation is a result of the merger of the lower limbs with variable fusion or complete absence of bones. Sirenomelia is universally fatal due to the associated lethal anomalies involving the internal organs, which are usually part of the VACTER or VACTERL complex. However, this sirenomelia-afflicted fetus is unique in being associated with VACTERL as well as congenital hydrocephalus.