That sounds really exciting but sorry my tube never did it for me to know. Curious as I was I did find this on the matter:


Reproduction:
Has been observed in aquaria (Wilkens 1990). Two individuals left their tubes; swollen and with tentacles intertwined, floating at the surface. Some weeks late a large quantity of small pinkish-orange eggs were observed floating at the surface. None of the larvae lasted through a developmental (Planula) stage; presumably from lack of food.

This was taken from this website: http://www.wetwebmedia.com/tubeanem.htm