Well, I had to do some googling. According to one story, challenge coins originated during World War I; another story says during the Vietnam War. My thanks to the Millers for their reply. I wonder if Paul was actually in the 1040 Causeway Detachment. Building the Navy's Bases in World War II mentions other Seabee units at Anzio but not the 1040th. So the memento remains a mystery.
At the Seabee museum, http://www.history.n...UnitHistory.pdf, I found this:
CBD 1040
"Formed at Camp Endicott in Jan. 1944, CBD 1040 sailed from Newport News, Va., on Jan. 29, 1944 and arrived at Bizerte in Feb. On March 8 one platoon began operations at Salerno. In May. six platoons were moved to the Naples-Salerno area. On July 31 two officers and 34 men were assigned to LST 525. On Aug. 1 two officers and 34 men wereassigned to LST 997. On Aug. 2 two of-ficers and 34 men were assigned to LST 32. Four platoons were ordered to Mar-seille. Aug. 28 and five more were sent to Toulon, Aug. 31. The personnel re-turned to headquarters at Bizerte in October 1944. On Nov. 9. another group of six officers and 97 men were assigned to duty aboard several LSTs. On Nov. 17, 1944, seven officers and 250 men were Nov. 23. The follnwing Aug. 8, the unit was inactivated."