By far the most abundant animal found in the Burgess Shale, Marrella splendens has become emblematic of this internationally renowned fossil formation. Described by Charles Walcott as a “lace crab,” Marrella was for years considered to be some sort of aberrant trilobite. After Harry Whittington’s examination of the animal, it was found instead to be a stem-arthropod — falling outside all other known arthropod groups. However, as with many Burgess Shale organisms, its exact position in the arthropod family tree is still uncertain.
Marrella serves as a perfect example of how incredibly common fossil animals can still be exceptionally strange, and how large sample sizes don’t always result in easy answers.
also may be referred to as the blue dragon, blue glaucus or blue ocean slug, is a unique species of sea slug. they are relatively small growing up to 3cm. and unlike their scientific name may allude to they are not only found in the Atlantic but are found throughout the worlds oceans, mostly in temperate and tropical waters where it floats upside down due to surface tension. they are predators and feed on organisms like the Portuguese Man o’ War and Velella(member of hydrozoa) as they are immune to their poison which they collect and use to their advantage like other nudibranchs. also even though those ads say they are aliens they are not!