Yes, relative of starfish.But I think it's actually a starfish.
I remember discussing that very thing over the dinner table. The scientists couldn't make up their minds. They wondered if maybe the wavey bits were eating/breathing tubules, but that would necessitate walking on the spikey bits, like an urchin.Very cool @DaveC426913 !
Its interesting that they had the original versions of Hallucagenia upside down (walking on what are now considered defensive spines).
I'm sure it was the scientist's fault and not your sister's.
She illustrated that too.Gould's book (Wonderful Life) was written before this was figured out, so he probably discusses it in a lot of detail.