Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, fluoresce green when photographed under deep blue light. Shetland Islands, Scotland, UK, June. Did you know? Se...

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, fluoresce orange when photographed under deep blue light. Shetland Islands, Scotland, UK, June. Did you know? L...

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, Shetland Islands, Scotland, UK, June

Sue Daly / Lightbulb seasquirts / tunicates (Clavelina lepadiformis) cluster on rock, Channel Isles, UK, July

SCOTLAND: The Big Picture / Curled octopus (Eledone cirrhosa) amongst a mearl bed, with Lightbulb tunicates (Clavelina lepadiformis) Shetland, Scotland, UK, August.

Sue Daly / Lightbulb sea squirt (Clavelina lepadiformis) Trondheimsfjord, Norway, July.

Andy Jackson / 2020VISION / Light bulb sea squirt (Clavelina lepadiformis), Endeavour Wreck, Kirkwall, Orkney, Scotland, UK, July.

Alex Mustard / A blue light fluorescence photo of light bulb sea squirts (Clavelina lepadiformis). The blue light source excites the fluorescent pigments in the sea squirts which emit light of other colours. The mud...

Franco Banfi / Tunicates (Clavelina lepadiformis) 'Le Formiche' dive-site, Ponza Island, Italy, Tyrrhenian Sea, Mediterranean Sea

Nick Upton / Group of Light bulb sea squirts (Clavelina lepadiformis) in rockpool low on the shore, Helford River, Cornwall, UK, August.

Sue Daly / Light Bulb sea squirt (Clavelina lepadiformis) Channel Islands, UK July

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, photographed under normal white light from a flashgun (left) and two examples photographed under blue light, on...