Archaeologist: "The tablet you found in the Ice Caves is strange. It's not part off the petroglyph, but the carving are in a similar style. Take a look at it in your inventory."
1- Open your backpack and tap on the tablet
Archaeologist: "What do you think it could be? Have you seen this cliff and these birds anywhere on the island?
Fly around and find the location shown on this tablet. It might lead to some answers."
2- Go to the place depicted on the tablet on Icestorm Island
3- Talk to Mildew
4- Find 3 elderberries in Berk
Mildew: "That will do, I suppose.
Hurry back and give me the berries. I hate to see Fungus down in the dumps!"
5- Deliver the berries to Mildew
Mildew: "Good. This will make his day.
Dig all you want, dragon-trainer. I keep my word... even if I don't like to. Tap on that dirt mound over there to start digging."
6- Dig for treasure near Mildew's hut
Mildew: "What is that? I didn't know there was a treasure buried on this island! Well, you got what you came for. Get off my property and scuttle back to your camp! I have things to do today..."
!: "This might be what the Archaeologist was looking for! He would be overjoyed to have it."
7- Give the petroglyph piece to the Archaeologist
Archaeologist: "My goodness! This looks like it might be a good fit for my petroglyph.
Take a look yourself. Go over to my table and tap on my petroglyph!"
8- Tap on the petroglyph on the table
Archaeologist: "It looks like the ancient Vikings who came to this island lived in peace with the dragons. That's fantastic! This is an amazing discovery, [Your Viking's Name]! We are one step closer to solving the mystery behind the petroglyph."