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