Wikipedia
Margaretia
Margaretia is a frondose organism known from the middle Cambrian Burgess shale. Its fronds reached about 10 cm in length and are peppered with a range of length-parallel oval holes. Its original interpretation as a green alga is not secure; it also resembles some alcyonarian corals, but a thorough redescription will be necessary to securely classify it. A relationship with the modern green alga Caulerpa is the most up-to-date consideration.