[Boatanchors] Need Help Identifying: Microphone (?)

[William]

Hello All,

I have seen an interesting item that I believe is a microphone.  It was in a nice little 'presentation' box and is in pretty good shape as far as I can tell.  My web search has returned absolutely nothing on this, but maybe someone out there can provide some details/history.

Here are the particulars:

1.  Hexagonal shape, about 3" - 4" across (did not measure).
2.  Outer housing seems to be made of marble.  Nice and heavy.
3.  Has a metal loop/hook/bracket on right and left sides.  Used for suspending in a frame?
4.  Two connector posts on the back face with bakelite knobs.
5.  Front face is metal, painted black, with a plated screen centered on the face.
6.  Printing across the top:  T.K.S. LYRIC HM-400L
7.  Printing across the bottom:  HODEN CO.

Any ideas, leads, information?

Thanks in advance for all of your help.

Best Regards,

William