If someone tries to give you a sea shell instead of money, they are not necessarily a Troglodyte.
I know where you went wrong with this answer ... you confused the Trilobites with the Troglodytes ... a common mistake ... it’s a dumb mistake but it’s also a common mistake.
Trilobites were marine animals which lived over 300,000,000 years ago ... they are the earliest known arthropods (which we all know means that they were invertebrates with an external skeleton and jointed limbs) ... they are related to, but not to be confused with, modern crabs.
I guess if you tried to use Trilobite fossils as currency, they might actually be worth something if you were in the right place at the right time ... however ... the Troglodytes were not famous because they used Trilobite fossils for money.
Try another answer.