Was it this one? It is called 'Death' and it is a ceramic tile design that Dali created in 1964.

If not, I suggest looking at this link:
http://www.dali-gallery.com/html/galleries/paintings.htm

and this link:
http://www.virtualdali.com/#galleryEarly1

Look through the extensive galleries

Dali has used the image of a starfish a number of times, so if you can remember any other information about the artwork, let me know and I will help you as much as I can.