heh, dangerous to correct the lady in charge of the forums LOL
But Wyvern is right, she isn't being sarcastic about the poster, just the product he is asking about.
Millet is basically a type of grain, most often used to feed budgies. It does mold and swell up...it probably won't cause blockage unless alot of it is consumed. It can also ferment...which won't be good, unless you want a drunk dragon on your hands.
It is also very slippery and unstable, thus your dragon or any lizard will sink through it and get little to no traction on it. All in all, it is a totally useless substrate for lizards. Great as a food source for mice and budgies though.
Oh and this stuff also can harbor grain mites and moths...adding a new collection of small bugs flying around the house.
Pretty much, of all the loose substrates available, the only good one for bearded dragons is washed children's playsand. Coincidentally enough, it is also the cheapest.
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PHLdyPayne