The eye creature / lava snake / segmented monster / dice monster / rock monster is blocking your path in the volcano. You can't jump over it until it rolls toward you and then unrolls flat on the ground.
You do not get or use a bucket on Astro Knights Island.
you jump over it
There is no treasure chest on Astro Knights Island.
There are no bird eggs in astro knights island.
No mines. But there is an underground chamber in Arturus. And the volcano passages are underground. (see related questions)
Sir peleas gives it to you at the bottom of the volcano cave. (see related question)
its on the island
How do you talk to the girl in the hay loft at astro knights island?
you just jump to the next one when you get near it!
On every island you have to be the one to save whatever needs saving. That includes the kingdom in Astro Knights Island.
On the Fire Planet, you get it from Sir Peleas when you reach the bottom of the interior of the volcano. (see related question)
Once you have built a new spaceship on Astro Knights Island, it will park on top of the castle whenever you leave the island.