Is this lens fungus?

[yiccciy]

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Like in the picture. Is this fungus? 
 

The weird thing is, I first saw things like this in  my 35mm summilux pre-a lens, after wiping everything clean and used for some amount of time, I then spot similar thing on this UV filter. 
 

Any help is appreciated!!

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[spydrxx]

It could be or it could just be crud dried on the filter. Have you tried wiping it off?

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[yiccciy]

2 hours ago, spydrxx said:

It could be or it could just be crud dried on the filter. Have you tried wiping it off?

I haven’t tried that. But even if it could be wiped off, I suppose it could also be fungus right? Do you happen to know how to tell the difference between fungus and crud?

[grahamc]

I don’t think fungus can be wiped off easily (would at least to some degree be attached to the glass or “etched” into glass).  So ease of removal may be your best way to diagnose. 
 

But other members would be able to advise better. 

[Mute-on]

Looks like crud. Fungus has tendrils spreading from a central point. That just looks like a circular blob. 
Spray with lens cleaner/isopropyl alcohol and wipe off. 

[Capuccino-Muffin]

Fungus on a filter, like that on open air? Impossible.

Fungus on a lens’ front element? Impossible.

Fungus grows in places where there is no air circultation.

[spydrxx]

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Try wiping lightly with isopropyl alcohol, crud should come right off. If it stays and possibly is fungus (highly unlikely) try a little hydrogen peroxide.

[yiccciy]

Thanks for all the reply! I wiped if off easily as suggested. So I guess it’s crud like suggested.