Fetus acardius amorphous is a rare fetal malformation occurring as a consequence of TRAP sequence.Prenatal diagnosis of acardiac twin is difficult. The main differential diagnosis is with placental teratoma and is based on the degree of skeletal organization and umbilical cord formation. A 32–year old woman delivered a healthy newborn at term gestation. An oval well defined mass, covered with normal looking skin, was connected to the placenta with a two vessel umbilical cord. X–ray examination of the mass revealed the presence of vertebral column. The rarity of fetal monsters without a functioning heart is emphasized.