seven-arm octopus
A species of octopus (Haliphron atlanticus). The name is usually written in katakana.
A seven-arm octopus was observed in the deep sea.
Katakana spelling is standard for this species name; usually written in kana.
Kanji spelling is rare and mainly found in specialized contexts; the katakana form is preferred.
The name カンテンダコ literally means 'agar-agar octopus', likely from the gelatinous appearance of the animal.