Interior Star Types[edit | edit source]
Interior stars can be split into three distinct types: Fixedstars, Rollstars and Fallstars. Fixedstars are fixed in a single unmoving location on the ceiling of a level, whilst Rollstars move around the ceiling of the level mimicking the apparent movement of a sun through a planet's sky. The final type of Interior Stars are Fallstars. Fallstars are Fixedstars or Rollstars that have run out of fuel and fallen away from the roof, crashing to the floor of the Shellworld level below.
Rollstars are the most common type of Interior Star.
Construction[edit | edit source]
Internal stars are thermonuclear devices comparable to tiny suns combined with exotic matter.
Fixedstars and Rollstars are anti-gravitative and consequently press themselves against the ceiling of the Shellworld level.
Heat Management[edit | edit source]
Like a normal star, each internal Star outputs an intense heat. Shellworlds can only provide sufficient cooling to maintain each level at an appropriate temperature by utilising all four dimensions of their hyperspherical structure. Even so, Rollstars can leave a heat trail across the ceiling in their wake which can remain visible for many hours or even days after a Rollstar has set.
Seasons and Day-Night Cycles[edit | edit source]
The various Rollstars on a given Shellworld level orbit the world along different orbital paths and with different orbital periods. On levels that have many Rollstars with different orbital periods, this leads to day-night cycles that are significantly more complex than those found on orbitals and planets orbiting a single star. 
Some Shellworld levels have vanes that can extend tens of kilometers from either the ceiling or the ground and can stretch halfway around a Shellworld level. Due to their size and position, these vanes cast large shadows onto the ground below and can cause localised nights, further complicating the day-night cycle of a Shellworld level. The majority of nights caused by a vane's shadow are temporary. However, in some benighted lands, vanes can cause localised areas to exist in a state of permanent night.
Maps produced by some sentient entities on Shellworlds include the shade limits and orbital periods of the various Internal Stars in addition to the geographical layout of an area.
Seasons on a planet or orbital are caused by an inclination of the body's axis of rotation relative to the plane on which it moves around a star. On a Shellworld however, seasons are driven by the number of stars that are visible and the length of the days relative to the length of the nights. The more stars that are visible above the horizon and the longer the days are relative to the nights, the higher the ambient temperature and vice versa.
Life of a Star[edit | edit source]
Interior stars were emplaced by the secondary shellworld species, i.e. they were installed by the species that settled the individual Shellworlds rather than by the Involucra, who built the Shellworlds. 
Internal Stars burn for a period of between 100,000,000 and 500,000,000 years before running out of fuel. As a star starts to runs out of fuel at the end of its life, the amount of light it produces can slowly reduce.
Once an Internal Star has run out of fuel, it can be replaced with a new Internal Star by a sufficiently advanced Involved species.
Fallstars[edit | edit source]
When a Rollstar or Fixedstar exhausts its fuel, it falls to the ground creating a final burst of heat and light if it enters an atmosphere. A star fall is a devastating event, particularly on levels predominantly comprised of solid ground. The fallen star pulverises earth and rock, turning them to dust and fire and sending projectiles the size of mountains soaring into the air. These projectiles produce a ring of smaller impacts and projectiles, ultimately creating a localised wasteland with the ground gouged out all the way down to the base layer of the Shellworld level. A star fall also creates clouds of dust and gas and years of spreading dissipating winters, terrible rains, failed crops and screeching dust filled winds.
The impact of a star fall causes the entire shield world to ring like a bell. Some sentient entities are much more sensitive to the ringing than others.
Whilst the falling of an internal star initially leads to massive localised destruction, over time a star fall leads to the creation of new rocks, landscapes and minerals.
Due to the life of an Internal Star being measured in hundreds of millions of years, there can be hundreds of millions of years between star falls on a Shellworld level.
Astrology[edit | edit source]
On some Shellworlds such as Sursamen, Astrologers ascribe influences to people and their lives from Fixstars, Rollstars and sometimes the actual stars of the milky way.
Known Internal Stars on Sursamen Levels 8 and 9[edit | edit source]
Level 8[edit | edit source]
- Domity - Rollstar
- Pentrl - Rollstar
- Guime - Rollstar
- Obor - Rollstar
Level 9[edit | edit source]
- Clissens - Rollstar
- Natherley - Rollstar
- Oausillac - Fixedstar
- Kiesestraal - Rollstar
- Uzretean - Rollstar
- Tresker - Rollstar
- Heurimo - Fallstar