Plohmble, plumble, plombol?

I recently watched Terry Jones' Barbarians documentary series, which is amazing and fascinating and gave me lots of really good ideas but I'm having a slight problem. During the segment about the Dacians, they showed some artifacts, one was this lead heart-shaped thing that is hung from a string and used in architecture to make straight lines. So my problem is this: I don't know how to spell the name of this thing so I can't research it.

Has anyone else seen the documentary or know what I'm talking about?

Plumb bob.

Do you mean a plumb bob?
http://en.wikipedia.org/wiki/Plumb-bob

Yes! Thank you so very much!