It’s the Colossal Squid!
I learnt this from my colleague’s 8-year-old! … and verified on Wikipedia!
The giant squid (genus: Architeuthis) is a deep-ocean dwelling squid in the family Architeuthidae, represented by as many as eight species. Giant squid can grow to a tremendous size (see Deep-sea gigantism): recent estimates put the maximum size at 13 m (43 ft) for females and 10 m (33 ft) for males from caudal fin to the tip of the two long tentacles (second only to the colossal squid at an estimated 14 m (46 ft), one of the largest living organisms). The mantle is about 2 m (6.6 ft) long (more for females, less for males), and the length of the squid excluding its tentacles is about 5 m (16 ft). Claims of specimens measuring 20 m (66 ft) or more have not been scientifically documented.
The colossal squid (Mesonychoteuthis hamiltoni, from Greek mesos (middle), nychus (claw), and teuthis (squid)), sometimes called the Antarctic orgiant cranch squid, is believed to be the largest squid species in terms of mass. It is the only known member of the genus Mesonychoteuthis. Though it is known from only a few specimens, current estimates put its maximum size at 12–14 m (39–46 ft) long, based on analysis of smaller and immature specimens, making it the largest known invertebrate.
I can’t wait till my little boy starts to teach me new and wonderful things such as this!