Your search for "Sea Monster 99" revealed the following:
Sea Monster (9ED) from Ninth Edition, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Daniel Gelon Card Text:Sea Monster can’t attack unless defending player controls an Island.
Sea Monster (Foil) (8ED) from Eighth Edition, available at 401 Games Canada. Rarity: Common Finish: Foil Artist: Daniel Gelon Card Text:Sea Monster can’t attack unless defending player controls an Island.
Sea Monster (7ED) from Seventh Edition, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: John Howe Card Text:Sea Monster can’t attack unless defending player controls an island.
Sea Monster of Theseus - MAMO-EN071 - Ultra Rare - 1st Edition from Magnificent Monsters 1st Edition, available at 401 Games Canada. Rarity: Ultra Rare Card Text:2 Tuners
Sea Monster (6ED) from Classic Sixth Edition, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Daniel Gelon Card Text:Sea Monster can’t attack unless defending player controls an island.
Sea Monster of Theseus - MP17-EN231 - Secret Rare - 1st Edition from 2017 Mega-Tin Mega Pack 1st Edition, available at 401 Games Canada. Rarity: Secret Rare Card Text:2 Tuners
Sea Monster (8ED) from Eighth Edition, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Daniel Gelon Card Text:Sea Monster can’t attack unless defending player controls an Island.
Sea Monster (10E) from Tenth Edition, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Brian Despain Card Text:Sea Monster can't attack unless defending player controls an Island.
Sea Monster of Theseus - RATE-EN081 - Secret Rare - Unlimited from Raging Tempest Unlimited, available at 401 Games Canada. Rarity: Secret Rare Card Text:2 Tuners
Sea Monster of Theseus - RATE-EN081 - Secret Rare - 1st Edition from Raging Tempest 1st Edition, available at 401 Games Canada. Rarity: Secret Rare Card Text:2 Tuners
Sea Monster (Foil) (10E) from Tenth Edition, available at 401 Games Canada. Rarity: Common Finish: Foil Artist: Brian Despain Card Text:Sea Monster can't attack unless defending player controls an Island.
Sea Monster (TMP) from Tempest, available at 401 Games Canada. Rarity: Common Finish: Normal Artist: Daniel Gelon Card Text:Sea Monster cannot attack unless defending player controls any islands.
Sea Monster (Foil) (9ED) from Ninth Edition, available at 401 Games Canada. Rarity: Common Finish: Foil Artist: Daniel Gelon Card Text:Sea Monster can’t attack unless defending player controls an Island.