Chlorophytes (Green algae).
<P>
<lI> Ulva (sea lettuce) has a multicellular thallus differentiated into
leaf-like  blades  and  a root-like holdfast that anchors the alga
against waves and tides.
<lI> Caulerpa has a thallus that is one multi-nucleate "supercell".
<P>
   Volvox is a colonial form.