A long extinct octopus.

Here's a picture of Pohlsepia mazonensis, along with a brief description. This is all lifted straight from the article in Paleontology.

Description of holotype. The specimen is exceptionally well preserved, providing a ventral view of its low relief, and is represented as a slight colour difference within the dark greyish brown siderite concretion, which is 80mm long and 50 mm wide. Light coloured features in the concretion to the left posterior (and possibly to the right anterior) of the specimen probably represent fluids expressed from the animal after burial. Distinct body, head and arms can be distinguished, as well as a number of internal and delicate external features.

The body of the coleoid, which has been compressed dorsoventrally, is subcircular and 35mm wide at its broadest point, with two distinct and symmetrical fins at its anterior. These fins are narrow and confined to the posterior margin of the coleoid. The mantle appears to have crumpled slightly, causing the posterior fins to tilt slightly to the anterior. An internal feature to the posterior of the coleoid may be interpreted as either an ink sac or a gut trace; ink sacs are common in Mesozoic coleoids, and the flask-like form of the trace is reminiscent of these. However, it is unusual for the ink not to be preserved, as the melanin of coleoid ink is stable. A similar feature was also described from Allison's specimen of an unknown coleoid (Allison 1987). The specimen shows no sign of any internal shell or phragmocone.

The head is identifiable but indistinct from the body, and possesses mandibular architecture, eyes, a funnel and arms. Mandibles and radula are preserved in the head region as strong impressions. The mandibles are articulated, although crushed and difficult to identify, and the radula is preserved in situ between them. Radula are commonly preserved in many of the Mazon Creek cephalopods. However, unlike these, the present specimen has its radula obscured by matrix and is otherwise unidentifiable. A short funnel may be visible at the anterior centre of the head, indicating the ventral aspect of the view, and is distinct and broadly central although no cartilagenous locking apparatus is present. The eyes are preserved as small patches of dark pigment which are spaced on either side of the
well-defined head, and the dark pigmentation is a typical feature of eyes in Mazon Creek vertebrates(?).

The arm crown is indistinct, although its component arms are clearly circumoral, and both short arms and longer modified arms (tentacles) may be distinguished. Only the right appendages are well preserved (left as seen in the ventral view), and comprise what appears to be four short arms (only three are definitely visible) and one longer tentacle. No hooks are present and suckers are not visible.

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