These specimens are fossil snail clusters found in the Green River Formation, a formation built up by two freshwater lakes during the Eocene epoch. These pieces are preserved mass mortality events, a quick die-off of a colony of snails preserved forever. They date to around 48 million years ago.

Sometimes known by the misnomer Turritella agate, these snails are actually Elimia tenera, a freshwater snail that flourished in the Green River lakes, rising to a population that numbered in the billions. Their reign was cut shot when a shifting climate collapsed their environment, leaving behind these incredible paleontological specimens.

Each specimen ships in a sturdy shipping container along with a certificate of authenticity. You can also browse our showcase fossil snail clusters in the collection below.

These fascinating specimens are clusters of Elimia tenera snails from the Green River Formation of Wyoming. This geologic deposit formed from two extinct lakes: Lake Gosiute and Lake Unita, around 50 million years ago. Because of its formation pattern, Green River has been a boon of extinct freshwater specimens, Elimia tenera among them. 

The abundance of such life made such snail colonies vulnerable to group dieoffs, now preserved in mass mortalities plates such as these. Based on the average density of these snail clusters, one estimate says that the formation holds one trillion fossil shells.

These group specimens are often known as “Turritella agate,” but this name is misleading. Turritella is a genus of sea snails that did not live in the freshwater deposits of the Green River formation, but “Turritella agate” has come to be used as common lingo for any such snail cluster. 

The difference between the two genera can be found in their shells, with Turritella having a long and thinner shell and then its freshwater cousins, whose shells are also axial and spiral shaped but a bit stouter.

Adding to the confusion around supposed “Turitella agate” are the different classifications used for the snails found in Green River, with both the Elimia and Goniobasis names being used in the past, now synonymized under Elimia. Additionally, these snail foster “agates” are no such thing. 

While these snails are surrounded in chalcedony, a crystalline form of quartz, its formation is not banded and thus not real agate. Names aside, fossil snail clusters such as these are incredible specimens, a snapshot of an ancient colony of long-extinct gastropods.