Hi phalfreak,
It is called that because herpers/froggers use it to line a VIVarium (vivariums hold live animals AND live plants, not like terrariums, which only have plants) for their pet amphibians. :) What it actually is
is sphagnum moss. If it is fresh enough, and then given high humidity again, it will in fact have some parts of it turn green as if alive again. Froggers use it with certain tadpoles, who need the high acidic nature that sphagnum moss has, in order to morph into frogs. Others use it for the "floor" of their "miniature jungle" they wish to create for frogs, newts, toads, etc. You can learn more about it at my website, or come talk over at the passiflora gardenweb board! :)...where I hang out. I just caught your post because of my interest in terraiums/vivariums...and the word FROG, of course :)
Hope I ansewered your question!
pollywogsworldoffrogs.com