Spreading Algae

Enchant Swamp
When enchanted land becomes tapped, destroy it.
When Spreading Algae is put into a graveyard from the battlefield, return Spreading Algae to its owner's hand.

Eighth Edition

Spreading Algae can enchant only a Swamp.
When enchanted land becomes tapped, destroy that land.
When Spreading Algae is put into a graveyard from play, return Spreading Algae to its owner's hand.

Urza's Saga

Play Spreading Algae only on a swamp.
When enchanted land becomes tapped, destroy that land.
When Spreading Algae is put into a graveyard from play, return Spreading Algae to owner's hand.

This card now has Enchant Swamp, which works exactly like any other Enchant ability. This means it can only be cast targeting a Swamp, and it will be put into its owner’s graveyard if the permanent it’s attached to ever stops being a Swamp.