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VStergios

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Need help to identify the following fossil. It was found in Milos, preserved in volcanoclastic sediment and diatomite. Data from a study in the area suggest late pliocene to early pleistocene. Looks like an echinoderma, but unlike any I've ever seen, since it's test appears to have layers and no apparent mouth (unless it's on the bottom part). I have even considered it being a cystoid or some coral, but I haven't had any luck researching my theories. Units on the pic with the ruler are cm and size is about 4.5cm. Any suggestion would be much appreceated! 

 

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Edited by VStergios
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Looks like one of the encrusting bryozoans I've been trying to figure out over here in Florida ...sometimes they enclose/encrust shells, echinoderms and sometimes they appear to be just masses...bryoliths. 

 

Pretty neat!

Regards, Chris 

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6 minutes ago, Plantguy said:

Looks like one of the encrusting bryozoans I've been trying to figure out over here in Florida ...sometimes they enclose/encrust shells, echinoderms and sometimes they appear to be just masses...bryoliths. 

 

Pretty neat!

Regards, Chris 

You could be right! Did the structure of the surface give it away? I have seen bryozoa cover a shell surface but never so completely and in so many layers.

Well, unless someone comments otherwise, I will consider your suggestion to be valid! Thanks for the fast reply!! Much appreciated!

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5b89ed9839d05_IMG_20180818_200232(2).thumb.jpg.2c9e23a6f7943c531d92524dc236ca56.jpg

IMG_20180818_200117.thumb.jpg.ff0d44041bc36949fad659162156a329.jpg

If you look close under magnification you'll see the structure and the very small zooids. Yours looks to be very well preserved.  Here's an example I have...I cant tell you genus/species--someone else may be able to do that with closeup photos of the zooids...nice find! 

Regards, Chris 

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6 minutes ago, Plantguy said:

5b89ed9839d05_IMG_20180818_200232(2).thumb.jpg.2c9e23a6f7943c531d92524dc236ca56.jpg

IMG_20180818_200117.thumb.jpg.ff0d44041bc36949fad659162156a329.jpg

If you look close under magnification you'll see the structure and the very small zooids. Yours looks to be very well preserved.  Here's an example I have...I cant tell you genus/species--someone else may be able to do that with closeup photos of the zooids...nice find! 

Regards, Chris 

That settles it then! Again thank you for the fast and accurate ID!

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When you are on a roll... just keep rolling :P

 

figure and text from:

 

Moissette, P., Cornée, J.J. & Koskeridou, E., 2010

Pleistocene rolling stones or large bryozoan nodules in a mixed siliciclastic-carbonate environment (Rhodes, Greece).

Palaios, 25(1):24-39   PDF LINK

 

Calpensia nobilis

image.png.c6e86a19359806808efb3b9ded2725ee.png

 

Spectacular accumulations of abundant bryozoan nodules (bryoliths) occur in the early Pleistocene coarse-grained, mixed carbonate-siliciclastic deposits of the Cape Arkhangelos Calcarenite of Rhodes, Greece.  These bryoliths are always associated with numerous bivalves (mostly ostreids and pectinids) and serpulid worms, together with other rarer skeletal organisms. The spheroidal bryoliths vary in diameter from 1 cm to 16 cm, and those with a more ellipsoidal shape range from 0.8 cm to 22 cm in length and from 0.7 cm to 16 cm in width; an elongated bryolith of exceptional size (40 cm) was even found.  The bryoliths are composed almost exclusively of the anascan cheilostome Calpensia nobilis and are nucleated on gravels, pebbles, or bivalve shells.  After settlement of bryozoan crusts, the bryoliths increased in size by repeated overturning of these mobile hard substrates by longshore currents.  The bryoliths developed at depths of 20–40 m on a flat shoal between emerged areas where bottom currents episodically accelerated during storms.  The currents also transported the bryoliths, together with other skeletal elements, into deeper settings (40–80 m) where they could continue their growth, upward or downward, or be colonized by other organisms.

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image.png.a84de26dad44fb03836a743755df237c.png

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6 hours ago, piranha said:

When you are on a roll... just keep rolling :P

It's actually a fairly common growth/feeding strategy for colonial organisms. 

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7 hours ago, Tidgy's Dad said:

It's a very beautiful specimen! 

Great find.:)

 

8 hours ago, ynot said:

Welcome to TFF!

+1 for bryozoan.

thank you both! :)

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6 hours ago, piranha said:

When you are on a roll... just keep rolling :P

Amazing info! You got the exact species and timeline :) Can't thank you enough, plus now I have even more reasons to visit Rhodes (had read somewhere about beautiful crinoid speciments in Arkhangelos)

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