In my 5.5g PFR tank there's a clay pot/cave of sorts. It's not a standard flower pot shape, it's wider at the base and has a narrower opening at the top. I plopped some Anacharis stems in it to hold them still.
My 10+ PFRs arrived on Tuesday. I did everything I was supposed to acclimate them. They seemed perfectly content, cleaning and exploring.
For the last two days I've only been able to find 2-3 of them at any given time. This morning I did a small water change, and for giggles I picked up the cave and carefully dumped the contents back into the tank. I counted 8 shrimp that swam out. Now they're all over the tank, cleaning and nibbling, acting like the happiest shrimps in the world.
I've had shrimp before, but never had a cave like this in the tank...
Is hiding normal behavior for them? Or did they wander in looking for a treat and forget how to get back out? :-P