We just learned about the Darwin's Frog.
Another frog is the Purple Frog.
This frog stayed hidden for a long time and nobody ever knew about it, because it kept itself buried in the mud, and only came out during big monsoon rainstorms.
It has a funny sounding croak that almost sounds like a chicken clucking.
(from: wikipedia - purple frog)
Kid Facts - Blast from the past: Southern Hognose Snake