【How-to】How do you spell kangaroo

Heptapods are very rare, but do exist. The sea star Luidia ciliaris naturally has seven arms. I suspect nearly all the heptapods on earth will be be echinoderms (sea stars, sea urchins, sea lilies), as these are the only animals with pentamerism (5-limbs), so likely would be the only ones with seven.