Sinuous, fuzzy fossil

[Daneyel]

My son found this in northwest Arkansas. I'm certain it's a common fossil, but multiple Google searches and a reverse image search yielded nothing. He really wants to learn about it, so I thought I'd post here. Thanks, in advance!

[hadrosauridae]

I'm no expert on the Ark area fossils, but I'm fairly sure this is a section of coral.  I'm sure someone who knows more can give a more details ID.  It helps in the ID process if you can list the county it came from, as well as the state.

[Kane]

My guess is branching bryozoan.

[doushantuo]

image from Hennig "Silurian bryozoa of gotland"(out of copyright)

edit: alterations mine

Edited April 10, 2023 by doushantuo

[Rockwood]

Assuming this is the standard thread count for blue jeans.  Size is an indicator used to help differentiate bryozoans from corals in some instances.  

[ClearLake]

@Rockwood is correct, size (among other things) is very important for distinguishing coral from bryozoans.  But before getting an actual measurement, I will say that this looks like a very interesting preservation of a bryozoan.  The original framework of the animal has been (mostly) dissolved away, leaving behind a cast of the internal spaces of the bryozoan.  Very cool looking!