Games

Quiz, myth or fact, and the trilobite-o-meter

Test yourself. Every answer comes with its source.

How to play. Pick an answer and the fact behind it appears, with a link to where it comes from. Without JavaScript, open “Show the answer” under each question.

The trilobite quiz

1 What does the word trilobite mean?
Show the answer
Three lobes. The word trilobite means ‘three lobes’. NHM
2 What were trilobite eyes made of?
Show the answer
Calcite crystal. Trilobite eyes were made of calcite, a crystal: the NHM says no other animal is known to have had that before or since. NHM
3 How long did trilobites last?
Show the answer
More than 250 million years. They lasted more than 250 million years, through six geological periods. NHM
4 What is the tail of a trilobite called?
Show the answer
Pygidium. Every trilobite had a head called the cephalon, a tail called the pygidium and a thorax in between. NHM
5 How could a trilobite protect its soft underside?
Show the answer
Roll into a ball. The thorax segments could bend, so a trilobite could curl into a ball, a bit like a woodlouse. NHM Rolling up protected its softer underside when danger came. BGS
6 How many trilobite species have been described?
Show the answer
More than 20,000. More than 20,000 species of trilobite have been described. NHM
7 Which is the largest known trilobite?
Show the answer
Isotelus rex. The largest is Isotelus rex, 72 cm long and 40 cm wide (the NHM page spells it Isoteus). NHM
8 What was the Dudley trilobite nicknamed?
Show the answer
The Dudley Locust. Local miners called it the ‘Dudley locust’, and it ended up on the Dudley County Borough Council coat of arms. NHM The BGS lists three nicknames: Dudley Locust, Dudley Bug and Dudley Insect. BGS
9 Who published the first known drawing of a trilobite, in 1698?
Show the answer
Edward Lhwyd. The first record of a trilobite is from Britain: in 1698 the Reverend Edward Lhwyd published a drawing of one found in Carmarthen. NHM
10 Which living animals might be their closest relatives?
Show the answer
Horseshoe crabs. Their closest living relatives might be horseshoe crabs. NHM
11 What did a 2022 study find on an Olenoides fossil?
Show the answer
Claspers. A Burgess Shale fossil of Olenoides serratus, described in 2022, shows two pairs of legs interpreted as claspers. NHM news
12 When did trilobites finally disappear?
Show the answer
Around the end of the Permian. They vanish from the fossil record just before the Great Dying at the end of the Permian, when 90% of animals were wiped out. NHM The British Geological Survey says they finally died out at the end of the Permian, about 250 million years ago. BGS

Myth or fact?

Eight statements. Some are true, some are myths.

1 Trilobites were sea animals.
Show the answer
Fact. Trilobites were sea animals and arthropods, the group that includes insects, spiders and crustaceans. NHM Geologists know they lived in the sea from the rocks they are found in and the other fossils found with them. BGS
2 Some trilobites are still alive in the deep ocean.
Show the answer
Myth. None survive: there is no sign of hidden living trilobites in the deep ocean. NHM
3 Woodlice are close relatives of trilobites.
Show the answer
Myth. Chitons, woodlice and sea isopods look a bit like trilobites, but none is closely related. NHM
4 Some trilobites had no eyes at all.
Show the answer
Fact. Others had no eyes at all, and may have burrowed in mud or lived deep in dark water. NHM
5 Trilobite fossils are usually found whole.
Show the answer
Myth. A cast-off exoskeleton often fell to pieces, which is why trilobite fossils are usually found as fragments. BGS
6 A trilobite is on Dudley’s coat of arms.
Show the answer
Fact. Calymene sits at the centre of Dudley’s coat of arms. BGS
7 Trilobites lived alongside the dinosaurs.
Show the answer
Myth. That makes them about 100 million years older than the first shark and 290 million years older than the first dinosaur. NHM They vanish from the fossil record just before the Great Dying at the end of the Permian, when 90% of animals were wiped out. NHM
8 Trilobite fossils help geologists work out the age of rocks.
Show the answer
Fact. Because there were so many and new species evolved fast, they are excellent index fossils for dating rocks. NHM

The trilobite-o-meter

How many trilobites long are you? Type your height and find out.

Your height, in centimetres

Type your height and press “Measure me”.

Our own arithmetic from the NHM’s figures: Isotelus rex 72 cm, Calymene about 2 cm, Acanthopleurella 1.5 mm. The size section has the sources.