Well, it's with a sad heart that I report the demise of my green sea hare that did such a fabulous job on my tank (posted photos of him eating cyano). My guess is this particular guy really lived on the nuisance film algaes and when he did too good a job, he starved. He never would take sheet algae.
BTW, Kirby Monster is what my DH and oldest granddaughter named him.
On a positive note, it's apparently not necessarily true that if they die in the DT, they will take out the entire system. I could tell he was failing, and watched him closely. I got him out after he didn't move for about 4 hours and he was beginning to smell really bad. But no bad effects on the tank, I'm glad to say.