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Lower end of the inside walls of a redwood cabana - the black discoloration/mold has been there (where the wood gets wet from drips/spray from rain). We had rains a week ago and went to clean the area and found these yellow things. We do have many spiders all around the year. Spider eggs? Yellow mold? something else?

  • No. Definitely not.
    – nobody
    Oct 31, 2021 at 0:01
  • Spider eggs are more uniform in size Nov 1, 2021 at 9:21

2 Answers 2


I think that's not sap but fungus. Because:

Those boards look old, and the black color looks like there's already fungus under the finish. If so, and if the yellow globs actually are new, "coming out after a rain, that's absolutely NOT sap. Sap comes out slowly over a couple years, and won't come out in rain.

If the globs are firm, are sticky/gooey and smell like sap, and aren't really new (you just never noticed them before) it's sap.

But if the globs are "squishy" like you say, or "watery", and really just popped out after a rain, they're not sap but fungus.


They are fungal fruiting bodies.

fungal fruiting bodies


To my eye it looks like golden jelly fungus or "witch's butter". Your board is rotting. But the good thing is that if it is witch's butter it is edible! Come back and let us know how that goes.

  • 26
    "But the good thing is that if it is witches butter it is edible! Come back and let us know how that goes." In general, it's a bad idea to eat any sort of fungus if you're not 100% sure that it's safe, because sometimes safe fungi and deadly poisonous fungi look almost identical.
    – nick012000
    Oct 30, 2021 at 1:39
  • 19
    Also eating an edible fungus growing on treated wood is dangerous. Fungi tend to collect many toxic substances. Oct 30, 2021 at 9:06
  • 2
    Pretty sure that “it is edible! Let us know how that goes” was a joke but agreed that it’s dangerous advice (even if not really advice!)
    – Josh
    Oct 30, 2021 at 13:12
  • 1
    I agree with @nick012000 and other responsible adult-type persons that it is a bad idea to eat things if you are not sure what they are. I see my answer has been edited. I take some solace in the fact that the wikipedia link still contains the term "edible".
    – Willk
    Oct 31, 2021 at 16:55
  • 2
    @Kris edible, but only once.
    – Nelson
    Nov 1, 2021 at 3:28

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