a missing ASW weapon... the Squid

[Jimbuna]

Literally ordered directly from the drawing board in 1942, under the auspices of the Directorate of Miscellaneous Weapons Development, this weapon was rushed into service in May 1943 onboard HMS Ambuscade. The first production unit was installed on HMS Hadleigh Castle, it went on to be installed on 70 frigates and corvettes during the Second World War. The first successful use was by HMS Loch Killin on 31 July 1944, when she sank U333; the system was credited with sinking 17 submarines in 50 attacks. By 1959, 195 Squid installations had been produced.

http://en.wikipedia.org/wiki/Squid_(weapon)