Is the penguins' HQ made of stone or concrete?

I think it's both. There are little stone lines on the walls but there aren't any on the floor.

From what I can see, I think it's made of concrete, because when you think about it, if it's made of stone, the surface itself would not be that smooth. But I'm 70% percent sure that it's concrete, you can see where the penguins are standing that it's smooth.

I've always assumed it was made of concrete. It seems a bit too smooth and uniform to be made of stone.

But I bet Gus would know for sure.

It would be made of concrete, since most things aren't made from stone since...... 4,000 YEARS AGO!!! XD

Well, concrete pretty much is just smoother stone. But it looks like concrete, it's much too uniform in color to be stone.

Remember in Madagascar how they dug out thier HQ with a plastic spoon? I don't think they can do that with rock. XD They probably dug it out than poured out the concrete for the floor and walls.

Im pretty sure it's concrete. It dosn't look alot like stone.