I think this is a peanut worm. Lurking under a rock.
from benthic grab
Collected from one cubic foot of backreef substrate plus water in the lagoon behind Carrie Bow Cay. CBCUBE_03_BCBC_157_Hemichordata_09.jpg
Today I observed several parchment-like tube that I believe are of acorn worms (class Enteropneusta) at University Beach, Corpus Christi Bay, Texas.
I visit this beach on a weekly basis, but I don't remember ever seeing these tubes. Maybe the strong winds brought them in?
In the biotic inventory of the Gulf of Mexico, Chris Cameron listed 5 species of acorn worms from the Gulf of Mexico, but only one species, Schizocardium braziliense Spengel, 1893, was reported in Texas. It actually was a new record for the Gulf, from Laguna Madre, Corpus Christi, where it was found to be abundant in 6 m of water. See more at BioGoMx:
Hemichordata is a phylum of marine deuterostome animals, generally considered the sister group of the echinoderms. They appear in the Lower or Middle Cambrian and include two main classes: Enteropneusta (acorn worms), and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a single species, Planctosphaera pelagica. The extinct class Graptolithina is closely related to the pterobranchs.