Intertidal area only
On the beach
Both intertidal area and subtidal areas
Subtidal area only
Feet
Spine
Nose
Mouth
Animalia
Strongylocentrotus
Echinoderms
Purpuratus
Pentamerous
Dome
Toothpick
Porcupine
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
Other sea urchins
Algae
Sea cucumbers
Small fish