Which is not an echinoderm?
a)sea star
b)sea urchin
c)sand dollar
d)spider

An echinoderm is a marine invertebrate. Starfish, Sea urchin, and Sand dollars are all echinoderms. A spider is an arachnid. Which means a spider is *NOT* an echinoderm.

D) Spider

Hope this helps. :-)

D)spider

Explanation:

Starfish, Sea urchin, and Sand dollar, all of following are echinoderms. A spider is a an arachnid.

hey, what do you need . just post the question and i may be able to you : )

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.