A species in my 5e pulp sci-fi game, which will probably be somewhat familiar to those of you that remember Star Frontiers...
Plasmoids are rubbery, elastic invertebrates. They can change their shape at will, creating a number of pseudopods as needed. Their skin is a flexible and surprisingly tough membrane. It generally is dull gray and lined with dark veins that meet at the Plasmoid’s two eye spots. The internal structure of a Plasmoid is much more chaotic than other species. Their central nerve bundle or brain and subordinate nerve clusters, numerous small hearts and other internal organs float in proteinaceous fluid with the consistency of pudding.
Plasmoids are generally good-natured, philosophical and thoughtful. They seem unconcerned with wealth, power or status symbols. They are infamous for their strange sense of humor. They love old jokes and groan-worthy puns. Human comedians who can’t buy a laugh on New Terra can get rich performing on Merkuro, though few are willing to make the trip to that forbidding world.
Homeworld: Merkuro
Average Size: 1.3 m tall, 1 m wide
Average Weight: 65 kg
Phenotypic Variation: Individual Plasmoids are not quite identical, but do not vary in predictable ways reflecting ethnicity or familial relationships.
Reproduction: Sequential hermaphroditism, offspring bud off of mother
Traits:
Ability Score Increase. Your Strength score increases by 2, and your Constitution score increases by 1.
Age. Plasmoids are fully mature within 1 year after budding and usually live up to 250 years.
Size. You are Medium or Small. You choose the size when you select this species.
Speed. Your walking speed is 20 feet, though this may be improved by adding additional limbs.
Blindsight. You have blindsight within 30 feet by using your chemical and tactile senses.
Elasticity. You can squeeze through a space as narrow as 1 inch along its narrowest dimension, provided you are wearing and carrying nothing. You also have advantage on ability checks you make to initiate or escape a grapple.
Grappler. Because of your elastic nature, you have advantage on attack rolls against any creature that you have grappled.
Resilience. You have natural resistance to piercing and slashing damage.
Shape Self. If you are not incapacitated, you can reshape your body to give yourself a head, one or two arms, one or two legs, and makeshift hands and feet, or you can revert to a limbless blob (no action required). You can have a total number of limbs equal to your Dexterity Ability score divided by 2. A Plasmoid needs at a minimum of 2 legs to be able to walk at base speed. A Plasmoid with 3 legs has a walking speed of 25 feet, and 4 legs or more has a walking speed of 30 feet.
As a bonus action, you can extrude a new pseudopod that is up to 6 inches wide and 4 feet long or reabsorb one into your body. This requires concentration until the start of your next turn. If you have three or more arms, you gain one additional unarmed melee attack or grapple as a Bonus Action during your turn when using an Attack action. Also, you can perform a Use Object Action as a Bonus action. You can use this pseudopod to manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour out the contents of a container without the use of a Bonus Action.
Languages. You can speak, read and write in Solar Trade Common and Merkuran.