My litle Marlowe has anxiety issues, heh. When I lowered the water in his first tank so I could move it out of the way of the second growout tank, he was totally freaked out. First, he tried to hide in a side-laying pot that was less than half his size, so only his tail really was in it. And then, I guess so I wouldn't "see him", he laid on his side and played dead, for a whole 40 minutes until i had the tank setup and moved him over. He tried the same possum technique under a decoration, but I guess his curiosity won out and he started exploring within a couple of minutes, haha!
Oh yeah, and then I had gotten a t-rex decoration with an air stone, so that every couple of seconds the bubbles open the t-rex's mouth, then it closes. Marlowe would spaz every time it closed for a while, then once he figured out what it was, he approached it slowly, twitching with every closure, but standing(swimming?) his ground until he got right in front of it, then took a bite at the t-rex's snout XD
In the morning, I saw he'd aparently had a fight with the beast and had it turned around from how I had set it, hahaha!