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At first glance, you might mistake them for flowers.
These beautiful creatures are crinoids, often called sea lilies. Despite their botanical appearance, they are animals—marine relatives of sea stars, brittle stars, sea urchins and sea cucumbers.
Their fossils preserve something wonderful: the remains of an underwater garden whose “flowers” were feeding.
A FLOWER WITH FEEDING ARMS
A typical stalked crinoid has a surprisingly elegant body plan.
At its base, an attachment structure anchors the animal. Above it rises a flexible column supporting a small, plated cup called the calyx. Branching arms spread from the top, forming the feeding crown.
The stalk lifts those arms into passing currents. Different species grow to different heights, allowing neighbouring animals to gather food at different levels above the seabed.
In dense communities, their crowns create a layered underwater landscape, with smaller creatures living among and beneath them.
This is a garden sustained by moving water.
HOW DOES A SEA LILY EAT?
A crinoid’s feathery arms are food collectors.
Tiny tube feet along the arms capture suspended particles. These morsels pass into food grooves and travel towards the mouth, which faces upwards within the crown.
The current delivers dinner.
Branching arms and their smaller side branches increase the collecting area, creating an intricate living filter. What looks like a delicate ornament is a remarkably effective feeding system.
LITTLE STONE BEADS
You are much more likely to encounter a piece of crinoid stem than a complete animal.
The skeleton consists of many calcite plates. In the stalk, these plates are stacked together like a column of tiny discs. Each stem segment is called a columnal.
After death, the tissues holding the skeleton together decay. Arms scatter, stems separate and the animal comes apart into a multitude of pieces.
Look closely at fossil-bearing limestone and you may notice small circles, rings or stars. Some resemble miniature washers. Others remain joined in short stacks.
These are fragments of animals that once stood above the seafloor.
Their abundance can be extraordinary. In some deposits, crinoid debris forms a substantial part of the limestone itself.
A complete fossil, with its crown and stem still connected, records a much rarer event: burial before that delicate skeleton could fall apart.
VANCOUVER ISLAND’S ANCIENT UNDERWATER MEADOWS
One of the loveliest places to imagine this vanished world is high in the mountains of Vancouver Island.
At Marble Meadows in Strathcona Provincial Park, limestone of the Buttle Lake Group preserves evidence of ancient marine communities.
During the Permian Period, long before these rocks became part of a mountain landscape, carbonate sediments accumulated on a shallow submarine platform. Crinoids lived alongside brachiopods, bryozoans and corals.
Their broken skeletons contributed to the limestone we see today.
The contrast is delicious: alpine meadows above, the remains of marine meadows below.
What is now rock beneath mountain air once lay beneath seawater. Subsequent geological movement and uplift, followed by erosion, brought that ancient seabed into view.
The fossils belong to the park’s natural heritage. Photograph them, enjoy their details and leave them in place for the next curious visitor.
SEA LILIES ARE STILL WITH US
Crinoids survived far beyond the ancient seas preserved in limestone.
Living members include stalked sea lilies and feather stars, whose adults lack a long stalk. Some feather stars can crawl or swim using their arms.
Watching one move is a lovely way to undo the illusion that these creatures are plants.
Modern crinoids also help palaeontologists interpret their fossil relatives. Their feeding, movement and anatomy offer clues to lives recorded only in stone.
