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