The organism shown is a free-living one that is anchored to the bottom of ponds and streams during the first part of its life cycle.

what is the common name of the group to which this organism belongs?

will mark brianlyest

cnidarians

echinoderms

arthropods

comb jellies

b

Explanation:

Echinoderms are a phylum of marine invertebrates that include starfish, brittle stars, sea cucumbers, sea urchins, sand dollars, and crinoids. They are one of the most diverse groups of marine invertebrates and play important ecological roles from the near-shore environment to the deep seas.

it cools slower in the earth meaning the crystals have more time to form than lava on the surface

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.