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