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