So I still can't find much info on them but I did find a freshwater puffer (Congo puffer) that looks a lot like it.....but it came to AI in a saltwater order. Maybe they're related somehow
On the plus side the sand puffer is eating well and seems healthy
Congo puffer pic
Info on congo puffers
http://www.seriouslyfish.com/species/tetraodon-miurus/
http://en.wikipedia.org/wiki/Congo_pufferfish
Any thoughts????