I found the grate section while scuba diving on and around the coral reef at Invasion Beach on Guam in 1974. The approximate location of the find is shown on the following picture.

Caution! This location is based on a 38 year old recollection.

Courtesy A Complete History of Guam, by Paul Carano and Pedro C. Sanchez,
Charles E. Tuttle Company, Rutland, Vermont, Tokyo, Japan, 1964, Following Page 368.

The grating material is very corrosion resistant. It must have been immersed in sea water for 30 years (1944-1974), and then has been mostly outside, in the weather, at my various homes since then. It has a thin coral-like encrustation. I scraped off a small section of the encrustation and found what looks like a grey metallic material. The material is non ferrous and it's specific gravity is 6.5 plus/minus 0.2. The specific gravity of iron starts at around 7.0 and for steel it's around 7.8.

Eventually I may place the grating on auction at eBay.com, but before that happens I'd like to be able to furnish prospective buyers with accurate information about it.

(2) What are the identities of the landing craft which were damaged or destroyed in the approximate area where the piece was found. (Eventually this may lead to identities of the servicemen on board the landing craft.)

Anybody who can shed light on these topics please contact me at the email address below. Answers and sources will be added where appropriate.