This monster's Japanese name, たまてがい tamategai is possibly a play on words of the 玉手箱 tamatebako from the famous Japanese fairy tale Urashima Tarō.
The "bako" (hako before "rendaku") in tamatebako means "box", while the "gai" (kai before rendaku) in "tamategai" means "clam". The "tamate" is two seperate words, with "tama" meaning jewel and "te" meaning hand, which would literally mean "tamate" translates to "Jewel Hand", but the words aren't agreed to impart any special meaning in this context, and might be merely phonetic.