Completion of the earlier steps in the Mod Deg trading sequence.
When you "Gaze into" Apollo's helmet, you will see a dark landscape, and only a glowing effect will be visible. Like the Creepy doll, it can only be used once every 8 seconds. This cooldown is shared with the doll, should the player have gone through the applicable trading process to have both items at one time.
The Goebie villager is different for each player. You may need to change worlds to find the specifically named Goebie to trade with. To discover which Goebie is looking for the helmet, use the helmet on any Goebie villager.
This is part of the Mod Deg trading sequence.
The protective headwear worn by the late space explorer, Apollo the monkey.