Pilot Long Murex
Brand: Pilot (Japanese)
Model: Long Murex (MR-500SS)
Production: October 1978 (For pen shown below)
Nib: Integrated Steel <F> Fine Nib
Filler: Cartridge/Converter (Pilot Cartridge or Pilot Con-20 squeeze converter, con-50 is not compatible)
This was one of my early 'grail' pens when I first got into fountain pens. It's a very sleek stainless steel design with a springy little clip on a snap-on cap. Unlike the Pilot Elite of the same era the Long Murex are surprisingly easy to disassembly without tools for a deeper cleaning (though a rubber band may help get a grip on the center joint). The nib is marked "<F>", but it writes somewhere in between Fine and Extra-Fine compared to some modern Pilot nibs I have. The nib is on the firm side, but it does have a slight amount of spring to it for a minor emphasis when writing.
An excellent resource I've found for information regarding the MYU and Murex line is The Tokyo Fountain Pen Scene.