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