  Solar tornadoes are dark vertical filamentary structures observed in the
extreme ultraviolet associated with prominence legs and filament barbs. Their
true nature and relationship to prominences requires understanding their
magnetic structure and dynamic properties. Recently, a controversy has arisen:
is the magnetic field organized forming vertical, helical structures or is it
dominantly horizontal? And concerning their dynamics, are tornadoes really
rotating or is it just a visual illusion? Here, we analyze four consecutive
spectropolarimetric scans of a prominence hosting tornadoes on its legs which
help us shed some light on their magnetic and dynamical properties. We show
that the magnetic field is very smooth in all the prominence, probably an
intrinsic property of the coronal field. The prominence legs have vertical
helical fields that show slow temporal variation probably related to the motion
of the fibrils. Concerning the dynamics, we argue that 1) if rotation exists,
it is intermittent, lasting no more than one hour, and 2) the observed velocity
pattern is also consistent with an oscillatory velocity pattern (waves).
