' holothuria tubulosa ', the cotton-spinner or tubular sea cucumber

rock sand sea life mediterranean cucumber texture aquatics holothurian closeup creature exotic cucumbers echinoderm stichopodidae invertebrate tropical environment aegean tubular marine fauna cottonspinner wild nature beauty holothuria tubulosa beautiful dive saltwater snorkeling underwater cotton spinner european animal ocean scuba natural biodiversity wildlife animals undersea background diving zoology flora biology aquatic aquarium water sealife aquaworld aqualife ecosystem species brown echinodermata grows length centimetres