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