They are definitely not "ducks", nor do they have any relation to "geo"-logy. In fact, they seem alien enough to be "from Mars" and, for all I know, possess a malign intelligence.

They are found mostly around Pacific Coast of the US and Canada, and in Japan they seem to serve as inspiration for "manga" of certain tentacled variety. A good info page is definitely in order to get the facts straight, but nothing can prepare you for the shock of seeing them for the first time:

Modern biologists easily classify it as large saltwater clam, a bivalve mollusk with a huge "neck", or a "siphon". How huge, you'll ask? Up to two meters in length.

Even their name is wrong, because it's pronounced "GOOEY duck". You'd think an epithet "gooey" would seem more appropriate for this bizarre creature, but it's not gooey in any sense. The name comes from a misspelling of "gweduc" (a native word), which means to "dig deep". Also, the "Elephant Trunk Clam" monicker fits them quite well.