crystal animation

Hi there,

i should do a Animation of a growing Crystal, or a crystallization. It should look something like this:
http://www.osf.co.uk/search_frm1.html?methods=search_results&dsp_next_set=1...

or, even better (and not so difficult to realize, i guess), like this here:
http://www.fotosearch.com/CRT813/002145cf/

Would be thankful for a hint, maybe someone even has done something similar...

Thank you, greets

to make the crystals grow like that.... the easiest thing to me would be to have the full screen of the crystals made.
perhaps in overlapping layers and then use masks to reveal the layers ( Maybe a circlemask getting bigger) That should
imitate the crystals growing.