Sponge question

[noodz.livejournal.com]

Hey all, does anyone know why the "soft tampons" sold through Meluna (http://www.meluna.org/epages/63898218.sf/en_GB/?ObjectPath=/Shops/63898218/Products/H-1048) aren't reusable? I primarily use a cup but every once in a while I use a sea sponge instead. I bought it years ago and as a vegan I no longer feel okay about using natural sea sponges, so I was looking at these synthetic ones. Can anyone think of a reason why I couldn't just wash these out and reuse them just like a sea sponge? Thanks in advance!