How do Urchins grow?

[big pat]

How do urchins grow? Do they lose their spines and then grow larger ones, or do they keep their spines and their spines grow larger while still attached?

 

[sergeant]

They usually grow larger while still attached. If the spines are falling off that means there is something wrong with it.

 

[big pat]

Oh snap...what do I do? My pencil urchin is losing his spines.