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