Nudibranch disappearance!?!

[aliciak]

Friday I got my shipment of cleaner crew items from SWF. At that point, I only had 2 clown percs in the tank. I took the time to acclimate everyone correctly and everything seemed to go well. My lettuce nudi was cruising around the LR and glass for 2 days, then stayed in 1 spot on the glass for 1 day, then just DISAPPEARED. I searched for him for a few hours and then to my horror found just his head stuck to some LR. EEK!
Prior to his demise, I never saw anyone messing with him. Any ideas who could have killed him (and eaten him up so quickly)?
PS: I know cleaner crews are supposed to clean up dead critters swiftly, but I had a dead sand sifting crab and no one touched him...he was DOA but I left him in the tank for 48 hours just to make sure he wasn't just in shock or something.

 

[lemonshark]

Nudis tend to cruse around your tank for two or three days and take a break. Then they try to go to the highest point and release themselves to be dragged by the current. They get cough on your filters and they easily break apart. When they are release in the water they release what I call “Web” that will help them anchor and prevent them from drifting away (One thing I really don’t like about Nudis). They are very fragile and they break easily. Check / Look harder around your tank, you might find other parts of its body. If not, then the part you found on top of your LR was the only part saved from your cleaning guys.
I get them near my house. I collect them and release them after they done their job. I sometimes collect 50 of them. One or two die, but at the end I release them and I keep just one or two.

 

[aliciak]

I can't really see that he would get caught on my filter...I only have the one filter for the Penguin 330 Bio-Wheel filter and none of him was stuck to that. Anyway, I don't think the Penguin has too much suction to have him get caught on it and break apart because I've seen snails and hermits cruise over the filter screen before and they never got stuck.
I felt really bad because he died within my "6 day guarantee" that SWF provides and all I could send back to them was his head.