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from shell hash.
The outer shell layer is mostly eroded, just a couple shells have some spiral ribbing left. (maybe the brown colour is just staining, but I found nothing similar that was not brown).

CORDANA CRASSA Toth

COLLECTION DATA – AC 2456, on wet wood near pond (developed after 3 wks in a moist chamber)
DESCRIPTION - short conidiophores, conidia 18-20x10-11u, 1-septate, dark brown basal cell, light brown apical cell, obclavate (like a pear).
NOTES – There was some taxonomic confusion about the name. Ellis described Cordana boothii Ellis in 1976 (Ellis, 1976) and included Cordana crassa Toth in his book on More Dematiaceous Hyphomycetes (1985). Later he illustrated and described Cordana crassa on Alnus wood in Microfungi on Land Plants (1997 new enlarged edition) with no mention of C. boothii. While the descriptions and illustrations seem remarkably similar he did not suggest that the two names were synonymous. In 2004 Lei Cai et al. (Lei Cai et al., 2004) proposed the synonymy as C. crassa Toth (=C. boothii M.B. Ellis) without further discussion. Cordana crassa Toth (Toth, 1975) predates the name C. boothii M.B. Ellis (Ellis, 1976) therefore the former is considered the correct name for this fungus.
Although the taxonomic situation seems to be resolved a recent key (Ling Qiu et al. 2021) described C. crassa as having unicoloured conidia. I would like to think that this was a misprint since the species clearly has versicoloured conidia (pale upper cell and dark brown basal cell.
This may represent the first report from N. America. MYCOPORTAL LISTS 0 COLLECTIONS AS C. CRASSA AND 3 COLLECTIONS (ALL FROM UK) AS C. BOOTHII

REFERENCES
Cai Lei ET AL. 2004. New species of Cordana and Spadicoides from decaying bamboo culms in China. Sydowia 56: 6-12.
Ellis More Dem Hyphos (1976)
ELLIS 1985 MICROFUNGI LAND PLANTS: CORDANA CRASSA ON ALNUS, CONIDIA WITH DARK BROWN BASAL CELL AND PALER APICAL CELL, 18-27X11-15U
LING QIU ET AL. 2021. Cordana sinensis sp nov from Southern China. Mycotaxon 136: 553-662.
Tóth (1975) Annls hist.-nat. Mus. natn. hung. 67:32; Ellis More Dem Hyphos (1976) described C. boothii as new but he later illustrated and described Cordana crassa on Alnus wood in Microfungi on Land Plants (1997 new enlarged edition). I assume he meant to include the former as a synonym of Toth's species.

Differs from Colus stimpsoni by the characteristic moderately deep revolving lines (although now worn); wider profile and smaller size. Historically, Colus islandicus has been found more often in NYC, while C. stimpsoni is more common in New England, according to Jacobson.

The AI thinks this is termites.

I'm going with an encrusting ascidian.

This is hanging from a rock in the low intertidal.

Second image is closeup of the part attached to the rock. Structurally it looks the same as the free-hanging part, but it was easier to image where it was thinner.