What is for this container called inside this reef tank?

[Ballyhoo]

this guy has on his YouTube video actually quite good video the upper left of his tank there's a clear acrylic looking container which has some red something in it? Does anybody know what that container is and what it's used for? Like you can put a nem inside it so can't get out? Or would it be like for a in tank refugium. ?

thanks!

 

[FUNGI]

NEM HOLDER....lots of different styles available......I just use a cheap in tank Petco separation/breeding box

 

[Solo McReefer]

Nem box
Mushroom box
Acclimation box
Anti aggression box

 

[Ballyhoo]

well, so I can get nems for my tank, alas.

 

[shakacuz]

well, so I can get nems for my tank, alas.

make sure the top edge is above water like in the picture, unless the box comes with a lid. 'nem's will roam otherwise!