Sandbelching Meerslug

I know Gameguy told me about how you can use the bombs on the Meerslug, but I still can't defeat this boss, and I've been stuck on it for a very long time. I have him 3/4 damaged, but now that he's making the walls, it just seems impossible to attack him to me.

So, does anyone have any tips on how to beat it?

Just keep hinting him with the pikmin and recall all the pikmin and stay away when he attacks. It took me a while before I beat him so it may take a few days.

I've been trying to do that, it's hard to ever get a chance to attack him though. Is there a way to make him turn on his back? I've done that a few times and was able to hit him much more easily, but I have no idea if that's just by chance or if there's actually a way to make him turn around.

It never turned it's back when I was fighting it so that's likely random. The rock Pikmin are also really good against this boss.