Sea Lamprey orPetromyzonis an agnathan. It is a marine organism. It lacks jaws and resembles an eel. It has a sucker-like mouth that is involved in filter feeding. It has seven brachial openings behind its eyes. They are anadromous and are usually found at depths of around 4000 m and can tolerate temperature ranges from 1.0 and 20 C.
So, the correct answer is 'Lamprey'.