Somewhat similar to deck-nails, but not so fine, and with square heads; for fastening cleats and the like.
They had long, square heads and flattened tails, with lateral propellers.
A cardboard tube, about three inches in diameter, is mounted between two square heads.
The square heads a are usually left black, though in exceptional cases they are finished.
Look at their square heads with no backs to them and their outstanding ears!
Note that square heads are supposed to be always unfinished, hence there is no standard for their sizes if finished.
Kit caught strange, deep-bodied fish with square heads, and was content.
Fair and honest treatment: Don't look for a square deal from them crooks (1876+)