Spot the difference

Many organisms that live today have barely changed their body shape in millions of years and look extremely similar to their ancestors. With the help of Sussex Wildlife Trust we have compared some of our Sussex chalk fossils, which are around 100 million years old, with modern animals that live in UK seas today.

Fossil Sea Urchin, Stereocidaris sceptrifera

Like many modern types living on the seabed, these sea urchins had spines as protection against hungry fish. This fossil is lacking it’s spines but you can still see where they would have been held.

Fossil of Stereocidaris sceptrifera, an ancient species of sea-urchin (or Echinoid).  Photo by Bob Foreman

Common sea urchin, Echinus esculentus

Common sea urchin, tube feet out©Paul NaylorSussex Wildlife Trust (1).JPG




Found on rocky shores, particularly around the north and west.

Fantastic facts:

An edible species, eaten particularly in Spain and Portugal.

Fossil fish, Ctenothrissa radians sp.

Fossil fish, Ctenothrissa radians sp., this is a rare complete example of this beautiful scaly fish which was found by Charles Potter in the late 19th Century.

Fossil fish, Ctenothrissa radians sp. Photo by Bob Foreman.

Black seabream, Spondyliosoma cantharus

black sea-bream juvenile©Paul NaylorSussex Wildlife Trust.jpg


The black sea bream, also known as a Porgy, is an omnivorous fish, eating seaweeds and small invertebrates.

Black sea bream breed in the Kingmere Marine Conservation Zone in Sussex between April and May. The males excavate a small shallow in the seabed, moving the gravel or sand around the edge to create a sort of crater into which the female lays her eggs. The male then protects the eggs until they hatch. He will fan them with his tail to keep them clear of sand or debris and wards off hungry predators, including smaller bream, wrasse and even whelks!

How to identify:

A large silvery fish, with an oval shape. Shaded bands running along the length of the upper flanks. It has a long single dorsal and anal fin and a small mouth. The tail is large and forked displaying a black band on it, most obviously noticeable on juveniles.

Juveniles usually have numerous broken yellow stripes running along the body. Spawning males are nearly completely black in colour, except for vertical white bars.


Found off south west Britain the Irish Sea and the English Channel.

Fantastic facts:

All black sea breams are born female! They change to males when they reach 30cm. All fish over 40cm are male.

Lobster, Palaeastacus dixoni

This rare fossil lobster was found in the Lower Chalk, Clayton, East Sussex and is from the Upper Cretaceous era. It has been preserved in wonderful detail.  First drawings of this fossil appeared  in scientific journals in 1850.   Collected by Henry Willet.

Lobster Palaeastacus dixoni Lower Chalk, Clayton, East Sussex.Photo by Bob Foreman.

Common Lobster, Homarus gammarus

common lobster©Paul NaylorSussex Wildlife Trust.JPG


A large crustacean, that grows up to 1 metre long, although more typically to about 50cm in lenght. Lobsters are a deep purplish-blue colour, with red antennae. They live in crevices and caves amongst rocks from the low tide mark and deeper. Their first pair of legs have massive grabbing pincers.

lobster film from Sussex Wildlife Trust on Vimeo.

How to identify:

Unmistakeable: other species of lobster are smaller and not the same colour


Found all round our coasts.

Fantastic facts:

Lobsters are nocturnal, hiding during the day in their caves.


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