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