It has fallen in and out of fashion for some time around here to pot hanging plants in wire baskets lined with coconut matting. Lo and behold, this year I found replacement mats for that purpose. They're large and cupped--large enough that I'll have to cut the one I bought in half, possibly into quarters, for my crabs to enjoy.
That is, if I put it in the crabitat. I don't think the fiber is treated with anything, just shaped. It isn't as thick as the mats you can buy in petstores, but, hey, it's cheap (two dollars for mine), large, and... I don't have a pet store nearby.