It is hard to believe that this twisty tube is a snail, but it is. Tenagodus vitis (Conrad, 1835) is the scientific name for this worm-like gastropod from the Claiborne Sand (Eocene) of Alabama. It was originally named by Conrad as Siliquaria vitis, a name still commonly used even though it was made a junior synonym by CoBabe and Allmon (1994).
This kind of gastropod with its awkward shell clearly didn’t crawl around. It was a sessile benthic epifaunal filter-feeder, meaning that it lived stationary on the seafloor filtering organic material from the water. Some of these sessile snails twisted their tubes around each other and formed a kind of gastropod reef.
The twisty part of Tenagodus vitis shows its true snaily nature.
The related Siliquaria anguina. (From Cooke et al., 1895, Cambridge Natural History, volume 3, Fig. 153.)
The discoverer of Tenagodus vitis was Timothy Abbott Conrad (1803-1877). He was a conchologist (one who studies shells) and paleontologist in New York and New Jersey, and he was a paleontological consultant during the early days of the Smithsonian Institution.
CoBabe E.A. and Allmon, W.D. 1994. Effects of sampling on paleoecologic and taphonomic analyses in high-diversity fossil accumulations: an example from the Eocene Gosport Sand, Alabama. Lethaia 27: 167-178.
Conrad, T.A. 1835. Fossil shells of the Tertiary formations of North America, illustrated by figures drawn on stone by T.A.Conrad. vol. 1, no. 3, p. 29-56, pl. 15-18 (pp. 77-110, pl. 15-18 in 1893 reprint by G.D. Harris [with pl. 19-20 not included in original by Conrad], reprinted 1963 by the Paleontological Research Institution, Ithaca, NY).