From Monkey Island wiki
The Summoning Artifacts are important, golden statuettes belonging to the Vaycaylians of the Jerkbait Islands. They are the only known way to find La Esponja Grande and are very valuable. They are shaped like the three spirits of the sea:
- The Wise Turtle is kept in an altar atop a cliff on Spoon Isle. Guybrush needs the help of LeChuck to open it up and get the turtle out of its hold. This leads McGillicuty's pirates to believe that LeChuck still has the artifact; they attack him and Guybrush must make a pyrite imitation turtle to get rid of them.
- The Noble Sea Horse is stolen by McGillicutty and his pirates, who prefer being infected with the Pox of LeChuck and don't want anyone to find La Esponja Grande. Guybrush can trick Trenchfoot and Hardtack into burying it with the noisy Pyrite Parrot so that he can find it and dig it up later.
- The Cranky Fish is hidden in a fishing well on Spoon Isle and can be caught when using a special, very old bait. The MerLeader acknowledges that the translation of the Cranky Fish's ancient name may be inaccurate.
When Guybrush has all three artifacts the MerLeader turns them into a summoning ball artifact and instructs Guybrush to throw it into the ocean and recite the ceremonial summoning words, which sound like a call to a pet. Three creatures, which have some body parts each of a fish, a seahorse and a turtle, emerge from the sea. They lead the way to the Manatee Mating Grounds, where La Esponja Grande rests.
- In the PS3 version, if Guybrush manages to get all the Summoning Artifacts, the player is awarded the "Artifacts of Life" silver trophy (a spoof on the words "facts of life") in the PlayStation Network Trophy Achievements, and when he throws the newly-formed summoning ball artifact into the ocean prior to the cutscene with Morgan LeFlay, Reginald Van Winslow and a manatee, the player is awarded a second gold trophy labeled "The BIG Finish" at the very end of the chapter.