Tigertail Cucumber reproducing???

Maybe this happens all the time, and I'm just out of the loop, but thought I would ask here, since my search resulted in nothing. 

I bought a complete set-up about a year ago, including livestock and corals. One of the critters I picked up, was a Tigertail cucumber. I see him every once in a while - usually in the morning, and he seems to be doing well. About a week ago, I noticed a second cucumber on the other side of the tank. Then yesterday I found a third one. It's not just moving around, since I can see all three of them (munching away) at the same time. 

Has anyone else experienced this? Were babies just hiding out in the live rock never seen before by me or the previous owner, or do these things reproduce asexually?

Thanks all!

Jamison Hensley

 

And I have a small yellow cucumber now that has split up into 3 or 4 really small ones.