Marzanna (Morana, Morena) is the West Slavic winter and death figure whose straw effigy is carried out of the village on the fourth Sunday of Lent and drowned or burned, a rite the Synod of Poznań tried to forbid in 1420 with the words 'do not permit them to carry around the icon of Death and drown in puddles'. The 13th-century Czech Mater Verborum glosses her with Hecate, and Jan Długosz in the 15th century likened her to Ceres; the effigy is dressed as a bride or a crone according to region. Whether she was a goddess or a personification of winter death is disputed, and the modern date of 21 March was fixed only in the 20th century.
Modern Practice
The practice is the procession itself: make the effigy, carry it out singing, burn or drown it, and come back with the green bough (gaik) - and do not look back, and do not touch her once she is in the water. It is a rite for ending winter and any season that has to end, not a devotion to the figure.