Would it crack if you boil it?
i know someone posted a pic of a betta that looked like it was being eaten by a terracotta fish.
/www.mexicanbeautygiftshop.com/images/TerraCottaFishCandle.jpg
/www.fishforums.net/index.php?/topic/378894-december-2011-fish-of-the-month-competition-entries/page__st__40