Spine
Feet
Nose
Mouth
Pentamerous
Dome
Porcupine
Toothpick
Subtidal area only
On the beach
Both intertidal area and subtidal areas
Intertidal area only
Because sea urchins have large numbers of relatively big eggs
Because a sea urchin's egg is relatively big
Because the eggs make great omlettes
Because sea urchins have large numbers of eggs
Purpuratus
Strongylocentrotus
Echinoderms
Animalia
Algae
Sea cucumbers
Small fish
Other sea urchins