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