disapperaring creatures in my tank

[erid]

Guys, I purchased a couple of cowrie Sea hares, and a tiger tail sea cucumber back in July.
I know that the cowries starve if they run out of algae, but both the cowries and sea cucumber disappeared within a few weeks "like a sock in the dryer".

Once in a wile I see a pure white mound of sand in different locations in the tank, I was wondering...

What do you think?

Erik

 

[Phyl]

Our cuke leaves "pellets" behind when he's through an area. If you're seeing pellet like formations of sand then he's still alive and kicking and likely busy behind the scenes. The cowries may have gone the way of the socks.