In article , Nick Maclaren
writes

They come in all lengths from about 1' to about 4'. I have one of
about 15" and another of about 2'.

The smaller versions are often called pinch bars and the bigger ones
crow bars - or Jim Crow to rail track workers. A pinch bar with a sharp
pointed end was used in latter-day marine times for teasling out knotted
ropes. Its name marlin spike came from the sharp point resembling the
nose of the marlin shark. Garrulous sailors would be gaffed with a
marlin spike.
--
Alan & Joan Gould - North Lincs.