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