A Greenwich Pikemans Pot, Circa 1620-30. Comprising wide-brimmed pot, made in two pieces with domed skull and low turned comb pierced with a hole, the base of the skull with recessed triangular feature on each side bordered by incised lines and above an embossed medial line between dome-headed rivets, downturned brim with recessed turned border with dome-headed rivets en suite, (some damage to the tip of the brim - see photos). A rare and impressive helmet. 

Notes: 

For a similar example see Bonhams - Antiques Arms And Armour From The Dr Peter Parsons Collection, LOT 150. 

Also D. Blackmore (1990) Arms & Armour of the English Civil Wars, Belmont Press, London. Page 66.