what did it do?

[MEIndrei]

Hello
So we have 2 (maybe 3) of these in the tank... They hitched a ride on the LR. The other day 2 of them climbed to the highest point of the LR and discharged a smoke like stuff for maybe 5 minutes (at 15 - 30 second intervals).

Were they reproducing?

 

[Bigjim10_4]

Can't really tell what it is from the picture but from the activity you are describing they sound like Stomatella. And yes that is how they reproduce. I also have them in my tank and they are a good critter to keep around.