The Lost Age trading side quest

First, sail to East Tundaria Islet. This is the snowy island just east of Tundaria Tower. Once there, hop over the platforms to the left and push down the log. Head back to the right bank of the river. Head over to the female penguin and push her right across the log until she is above the male penguin. He will give you a Pretty Stone as a reward.

After getting that, sail to SE Angara Islet. This is the island just northwest of Lemuria. Head up two flights of stairs. Ignore the first box that you see. Push the second one onto the ground. Now push that one space to the east of the puddle. Head up to find the other box. Push it on top of the other box. Cast Frost the puddle, and then hop from the box onto the ice pillar. Climb up the vines to find a bird's nest. Use Mind Read. You'll exchange your Pretty Stone for Red Cloth.

From there, sail to the island that is due south. This is N Osenia Islet. Head to the western part of town and use Sand to get across the gate. Mind Read the cow to exchange your Red Cloth for Milk.

Next stop is West Indra Islet. This is a hard-to-see island fitted between the continents of Gondowan and Indra. Once there, use Mind Read on the dog. You'll trade your Milk for a Lil’ Turtle.

The final stop will be the Sea of Time Islet. This is the island southeast of Lemuria. Mind Read the turtle and you'll give away your Lil’ Turtle. In return, the turtle will show you his secret spot, the Islet Cave!