The motor is usually supported on a platform at the back of the instrument, its drivingwheel being connected to the shaft of the paper roller by means of a spirally wound steel band.
In the manufacture of the cable the wires are first enclosed in the paper, which is applied sometimes longitudinally and sometimes spirally.
In addition to tentacles, there may be marginal cirri (Laodice) with a solid endodermal axis, spirally coiled, very contractile, and bearing a terminal battery of nematocysts.
Another type exists in Rhea and in the Anseriformes, greatly specialized by being spirally twisted and partly reversible like the finger of a glove.
The cones, about the size of a small walnut, bear spirally arranged imbricated scales which subtend the three-angled winged seeds.