Which species does this foraminifers belong to?
It is cemented with sand grains in a Polichete sandtube
Dear Mr. Ceci,
the morphology and the host structure you describe make me think of something like a coprolite (fossilized feces).
Best regards
H.G.Dill
It's more likely to be a degraded benthic foraminiferan test.
Crispin's right: it is an inernal mold of a biseriated foram, most likely benthic.
Dear colleagues,
how did a single foram get into a borrow filled with sand and cemented ?
H.G.Dill
dimensioni? la mia prima reazione è stata che fossero denti, o comunque strutture per sbriciolare, come ne hanno anche i decapodi. ma riguardandolo, mi sembra più una teca rovinata
Secondo la maggioranza infatti si tratta della teca rovinata di un foraminifero bentonico, le dimensioni sono inferiori ai 3 mm.
It indeed strongly resembles a biserial benthic foram, possibly an agglutinated Spiroplectinella. However, it is rather huge (almost 3 mm in length) and the color is unusual. Can you liberate the specimen form the tube, so that the symmetry can be better assessed?
I would not hurt the tube, I want to make better pictures, to better observe the symmetry
Hi Massimo,
I agree with the response of biserial benthic foram.
Best regards,
Hakima
I agree with it being an agglutinated foram, but I am not convinced that it is biserial throughout. The early whorls appear to have >2 chambers.
hello to all, a researcher in contact with one of my collaborators has classified this specimen of foraminifera as Septotexularia rugosa, are we all right?
Dear Massimo
I assume the isolated specimen is the same specimen as before. It could indeed well be Septotextularia rugosa (note spelling) as very similar specimens are depicted under that name online from marginal seas in the western Pacific. It is also given in the World foraminifera database: http://www.marinespecies.org/foraminifera/aphia.php?p=taxdetails&id=492613
Without a holotype description (apparently in Chinese) I cannot judge this any further.
Hello Robert,
exactly, the isolated specimen is the same specimen as before, is its dark color a typical character? in the meantime, the search for the oroginal description of the holotype continues
To me the dark color is rather unusual for agglutinated foraminifera, but it may depend on the grains it is composed of, or on secondary staining (sulfides? manganese oxide?). In contrast the specimens of S. rugosa on the website below (and in the image attached here) are unusually pale for agglutinated taxa (to me at least).
https://www.sablesdumonde.com/en/foraminiferes/bunaken-paradise-of-foraminifera/
Despite from the exact genus or species name, I have seen many specimens of similar large (>1mm) agglutinated Foraminifera from Cretaceous deepwater Sediments (Helvetic and Flysch-Units) which are dark grey to almost black in colour. They show the same coloration as the rocks from which they were gathered. Your specimen may therefore be reworked from older sediments and incorporated into the worm tube.
Dear Massimo
I should have asked this before: where did the specimen came from? If it's from Mediterranean waters, the suggestion of Holger, that it may be reworked from Cretaceous rocks, becomes very plausible. Septotextularia rugosa seems to be restricted to the western Pacific and eastern Indian Ocean.
The specimen comes from Hong Kong, unfortunately we do not know the exact origin, we can perhaps restrict the field of investigation to the range to the species of Pectinatria using foraminifera to build the shell?
I'm not quite sure what you mean. At any rate, Hong Kong is in the right region for S. rugosa and, judging from the dark staining, it may have been reworked from Holocene or Pleistocene sediments..
hi folk!
beside this nice dark guy, it seems that all other grains might be or biogenic origin....some terribly preserved Amphistegina? next to the second picture it seems they have a planispirally coiled test....
in fact, the thing that amazed me is that close to a few hundred biogenic shells there is one and only one very different in the taxonomy, in the feature, in the degree of preservation, for the enigmatic origin
Dear Massimo,
do you have any other pics of the Polichete sandtube? any idea of the depth it was collected?
I found similar specimen from Red Sea, though not dark in colour...
The photo of the polichete sandtube seems to belong to “ice cream cone worms” or “trumpet worms” (Family Pectinariidae Quatrefages, 1965). Such tubes are nice modern analog of some Eocene trace fossils we found in the Caribbean. The lining is composed of LBF tests. In your case, maybe Amphistegina?. However, the Eocene specimens are built from operculinids and lepidocyclinids. Results of this finding will be published soon in Ichnos.
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