The beaded sea cucumber is a bizarre creature that resembles an alien life form from a science fiction movie. It is an animal, despite having no eyes, no true brain, and no distinct sensory organs. Clusters of nerves allow it to sense changes in light and to have some tactile sensation, but even those are very rudimentary. Sea cucumbers are among the most numerous animals in the ocean, and at extreme depths, they are a dominant presence, accounting for the majority of biomass in lightless and cold environments that are less welcoming to fish and other creatures. They find food by filtering the water for small chunks of decaying pant matter, breaking them down even further as they consume them and excrete a more processed end product. This allows bacteria to continue the process and break down the rotting vegetation even further. The sea cucumber plays a critical role in keeping the oceans clean. Like all other sea cucumbers, the beaded sea cucumber dwells on the ocean bottom, contracting and expanding for locomotion. It has no feet and no other means of propulsion. The strangest looking part of this long, serpent-like animal is the mouth. It has 15 feathery tentacles that are constantly in motion, opening up and sweeping the water for food. They close and retreat to the mouth to pass particles into the digestive tract. Their rhythmic movement is strange to watch, giving the mouth an appearance that resembles many of the alien creatures that we have seen in fictional shows over the years. A recent series called "Stranger Things" features a supernatural villain with a similar look. The comparison between these two creatures has not gone unnoticed. In the animal world, most limbs are evenly numbered because most animals are designed in a bilateral manner, with two reasonably symmetrical sides. But sea cucumbers are designed more like a ring with five parts, much like a starfish. They have symmetrical features in each of the five body parts, allowing for this animal to have an odd number of tentacles. If the sea cucumber encounters a drastic change in light, or if it senses motion, it will pull in its vulnerable tentacles and contract, retreating to safety. Sea cucumbers are generally harmless to humans, possessing no ability to attack anything, but some are coated with an irritant or even a toxic slime that can cause injury to eyes or other mucous membranes. It would be wise to avoid handling sea cucumbers without understanding which ones are safe. In many tropical areas, sea cumbers are an important food source.