Moreover, species of paper nautilus which is similar to the blanket octopus are also drifting in the ocean, and the female of which secretes shells from its arms and wraps itself in the shell and incubates eggs in it.
またムラサキダコに縁の近いカイダコ類は、同様に外洋で遊泳生活をし、雌は腕から貝殻を分泌してその中に包まっており、この貝殻の中で卵を保育する。