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