Wooden Ramps were designed to destroy incoming landing craft. The ramps were a simple design that consisted of wooden logs arranged so that the longer of the logs was angled upwards and supported by two (and sometimes four) shorter logs. Pointed towards the beach, this configuration would flip over small craft and send their occupants into the cold water of the English Channel. Although mines were sometimes added to the tip of the longer log, exposure to salt water often corroded these explosives and they were not as effective as originally planned.
Element C or also called a Belgian gate.
Tetrahedron
Stake. Some stakes were used in the fields behind the beaches to prevent gliders from landing on open pastures.
Source: Saving Private Ryan On-line Encylopedia -- www.sproe.com