Coarse-textured sea sponges (real or fake) for painting

I’ve looked around in the local shops, but all the sponges are artificial, finely textured and square. I would like some larger, coarsely textured and irregular ones like some sea sponges for my painting work, like this:

Has anyone seen these for a reasonable price in Taipei, or does anyone have used ones they’re planning on throwing away?

I bought some at a baby shop for bathing my kids but they were quite expensive at 200nt+

Thanks! I might try there, or down at the art shops by Shida.