My vote is they can. They can get sucked through powerhead strainers, and back when my reef was young I had a carpet anemone that buried its foot in the black dolomite, when through the undergravel filter and attached to the bottom glass (yes, my reef is that old! ). After it ate a couple clownfish and a yellow tang I sold but could not separate it from the filter plate. So, the buyer got an well fed anemone and a free undergravel filter plate.
I think the odds of it eventually happening are pretty good. Though there are so many variables it's hard to say.
yes i have seen them squeeze into very tiny spots but i dont see them being able to fit entirely through the eggcrate, when going through powerheads are they making it all the way through or just hitting the impeller and getting beat up? i honestly dont know. hope someone has an answer
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