Which statement describes a disadvantage of nonrenewable resources? a. it is hard to collect large quantities of them at a time b. they inconsistent or unreliable as an energy source c. they are expensive to collect and transform into energy d. it is difficult to change the habit of using the resource

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

i'd say that the moon rock is about 2.2 billion years old.