I've seen this icon in a few apps and video players but most notably in Arment's Overcast app (full screen shot at the bottom of this issue). This is the forward icon:

I googled around but can't find a formal name for it so please let me know if you know of one. I also searched "seek" and "forward" in the issues and found nothing. This might be too specific so no hard feelings if this is ignored. I will add more examples to this ticket (if it further supports my case) as I find them.
This would be used in video or audio player to seek ahead or back 30. Additionally I'm not sure if 30 is the best default. If the community agrees, it could be worth having a 15, 30, 60 option but I realize that's a lot.
This is the full screen shot:

my Idea, make it empty also make numbers and stack it.
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my Idea, make it empty also make numbers and stack it.