Simplify the following text for a Grade 10 native English-speaking person.
Original: Cuttlefish are sea animals of the order Sepiida belonging to the Cephalopoda class ( which also includes squid , octopuses and nautiluses ) .
Simplified: Cuttlefish are marine animals of the order Sepiida . They belong to the class Cephalopoda ( which also includes squid , octopuses , and nautiluses ) .