You can tribute a face-down Fish, Sea Serpent, or Aqua-type monster to activate the effect a of Piercing Moray.
Tributes for cost
This card gains ATK
An absolutely underrated card! This card is actually only useful after you have a near perfect water deck. This card will help you in many sticky situations, its best outstanding feat is against weevil and téa decks to deal massive damage to set monsters; even against toon decks it has its uses. You'll be suprised how much in handy this comes when coupled with Beautunaful and Needle Sunfish, especially in the late game. I switched out one Uminotaur for this and I'm keeping it!