Spidery Corrosion?

What causes this threadlike corrosion pattern? Is it dangerous?
Actually it looks very pretty and adds to the gothic ambience of this 1880s blade but should I worry about it?

I've seen similar on some blades of mine. Looks good on that blade. Corrosion for sure but I can't say how it gets there.
Stored wet? Salty air maybe? Don't know.
I chalk it up to character and leave it for the appearance as it's usually more work than its worth to remove.

I've restored a few NOS Filarmonicas with this spidery corrosion I did a EPBD not so long back all I will say it was deep into the steel and it wouldn't come out.

Reminds me of this story by Poe:

http://xroads.virginia.edu/~hyper/poe/cask.html

Seraphim said:

Reminds me of this story by Poe:

http://xroads.virginia.edu/~hyper/poe/cask.html

Click to expand...

So any mettallurgists got an explanation of how this corrosion pattern is caused then?
I read one theory on a science site that it was caused by spiders webs, which makes it even more gothic!

What were the scales made from?

I had one like that and suspected Cell Rot.

Buffing and rescaling solved the problem.

H Brad Boonshaft said:

What were the scales made from?

I had one like that and suspected Cell Rot.

Buffing and rescaling solved the problem.

Click to expand...

Celluloid scales - but the area enclosed by the scales is fine, and it takes a great edge.
The cell rot I've seen looks more like a hazy mist.

I have seen Cell Rot where it turns the whole blade black, the light red/brown rust, black blotches and black pitting and rusting only up to the scale line. There are many forms of sell rot. Apparently there were several formulas used depending on the color or the design they were looking to achieve.

Tortoise imitations seem to break down and stain the steel behind where the darker spots were. A similar thing happens with crack ice scales and there is a correlation with the scale pattern and rust pattern.

How the razors were stored also play a large part in causing the chemical breakdown. The ones I have seen similar to the OP were pitted not just stained. Yours may have been stored next to a razor that was off-gassing and the scales actually protected the steel.