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