Sea Urchins are marine animals belonging to the phylum Echinodermata. Within this phylum, they are classified under the class Echinoidea.

Sea Urchins are marine animals belonging to the phylum Echinodermata. Within this phylum, they are classified under the class Echinoidea.

Let's look at the options:

• A) Crinoidea: This class includes sea lilies and feather stars.
• B) Echinoidea: This class includes sea urchins and sand dollars.
• C) Ophiuroidea: This class includes brittle stars and basket stars.
• D) Holothuroidea: This class includes sea cucumbers.

Therefore, the Sea Urchin is an example of the class Echinoidea.

The final answer is $\boxed{\text{B}}$