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