Target 1 face-up monster on the field; its ATK and DEF become half its current ATK and DEF until the end of this turn. Once per Chain, when a Trap Card is activated while this card is in your Graveyard: Special Summon this card as a Normal Monster (Aqua-Type/WATER/Level 2/ATK 1200/DEF 0). (This card is NOT treated as a Trap Card.) If Summoned this way, this card is unaffected by monster effects, also banish it when it leaves the field.
Since Paleozoic Hallucigenia, as a monster, is summoned at such a low level, Amulet of Ambition is a great card to use for a powerful attack boost.
Here are some other Paleozoic monsters you could use as they are all able to trigger each other's special summon effect. Paleozoic Pikaia and Paleozoic Marella is a great way to send Your Paleozoic monsters to the graveyard. Paleozoic Leanchiolia can return banish Paleozoics to your graveyard.