What is this spa(?) grate/nozzle called?

[thespacepope]

I have been meaning to ask this question for a while but kept forgetting to take and post a photo.

I have this odd nozzle/grate thing in the side of my spa but I have no idea what it is called or what it would be used for. It is a grate of some sort positioned over a nozzle thing with some fins attached. The pool was build in 1986 or 1987. This doohickey seems to just flop abound but does not seen to really aim or do anything special.

Any ideas?

 

[gwegan]

Bump

 

[pabeader]

Does it spin/rotate?

 

[thespacepope]

It seems like it may have spun or rotated at some point in time but now it just flops around.