There are still places where all planting has to be done with a big steel spike.

This would involve hammering a barbed steel spike into the touch-hole, which could be removed only with great difficulty.

Radio transmitters are housed in the lower part of the concrete tower with antennas attached to the steel spike.

They guided it home and drove in steel spikes to bolt it in place.

One possibility involved the replacement of the steel spikes with alternatives made from carbon fibre, although the report underlined the necessity for extensive testing.