Cute little puzzle game, but I have a few suggestions.
The way the levels were set out encouraged me to find easier ways solve it by going to the edge of the grid rather than going through the middle and dealing with the obstacles, which make the solve less satisfying.
I also found it a bit tedious to have to click and drag the ship around, this could be helped by adding more visual feedback when you tap the ship - or maybe let the player tap the ship, then show all the squares the ship can move to, and they can tap again to choose the move location.
In terms of progression, I think it could be a lot more granular, eg adding one shell and getting the player to deal with it.
Nice job, I love puzzle games and would like to see more of them!