Acronym	seside
TOCID symbol	sIID*, ssI
Name	small snub icosicosidodecahedron, snub disicosidodecahedron, holosnub icosahedron, hastur
	© ©
Circumradius	sqrt[13+3 sqrt(5)+sqrt[102+46 sqrt(5)]]/4 = 1.458190
Vertex figure	[5/2,35]
Colonel of regiment	(is itself locally convex – no other uniform polyhedral members)
Snub derivation
Face vector	60, 180, 112
External links

As abstract polytope seside is isomorphic to sirsid, thereby replacing prograde icosahedral triangles by retrograde ones.

As mere alternated faceting the 2{3}-compound is regular, for sure. It is by the afterwards to be applied step back to equally sized edges that those compounds become non-regular.

Incidence matrix according to Dynkin symbol

s5/2s3s3*a

demi( .   . .    ) | 60 |  2  2  2 |  1  1  1  3
-------------------+----+----------+------------
sefa( s5/2s .    ) |  2 | 60  *  * |  1  0  0  1
sefa( s   . s3*a ) |  2 |  * 60  * |  0  1  0  1
sefa( .   s3s    ) |  2 |  *  * 60 |  0  0  1  1
-------------------+----+----------+------------
      s5/2s .      ♦  5 |  5  0  0 | 12  *  *  *
      s   . s3*a   ♦  3 |  0  3  0 |  * 20  *  *
      .   s3s      ♦  3 |  0  0  3 |  *  * 20  *
sefa( s5/2s3s3*a ) |  3 |  1  1  1 |  *  *  * 60

or
demi( .   . .    )    | 60 |  2   4 |  1  2  3
----------------------+----+--------+---------
sefa( s5/2s .    )    |  2 | 60   * |  1  0  1
sefa( s   . s3*a )  & |  2 |  * 120 |  0  1  1
----------------------+----+--------+---------
      s5/2s .         ♦  5 |  5   0 | 12  *  *
      s   . s3*a    & ♦  3 |  0   3 |  * 40  *
sefa( s5/2s3s3*a )    |  3 |  1   2 |  *  * 60

starting figure: x5/2x3x3*a

β3β5o

both( . . .    ) | 60 |  2  2  2 |  1  1  1  3
-----------------+----+----------+------------
sefa( s3s . (r)) |  2 | 60  *  * |  1  0  0  1
sefa( s3s . (l)) |  2 |  * 60  * |  0  1  0  1
sefa( . β5o    ) |  2 |  *  * 60 |  0  0  1  1
-----------------+----+----------+------------
      s3s . (r)  ♦  3 |  3  0  0 | 20  *  *  *
      s3s . (l)  ♦  3 |  0  3  0 |  * 20  *  *
      . β5o      ♦  5 |  0  0  5 |  *  * 12  *
sefa( β3β5o    ) |  3 |  1  1  1 |  *  *  * 60

or
both( . . . ) | 60 |   4  2 |  2  1  3
--------------+----+--------+---------
sefa( s3s . ) |  2 | 120  * |  1  0  1
sefa( . β5o ) |  2 |   * 60 |  0  1  1
--------------+----+--------+---------
both( s3s . ) ♦  3 |   3  0 | 40  *  *  as coplanar pair of {3}
      . β5o   ♦  5 |   0  5 |  * 12  *
sefa( β3β5o ) |  3 |   2  1 |  *  * 60

or
both( . . . ) | 60 |   4  2 |  2  1  3
--------------+----+--------+---------
sefa( s3s . ) |  2 | 120  * |  1  0  1
sefa( . β5o ) |  2 |   * 60 |  0  1  1
--------------+----+--------+---------
both( s3s . ) ♦  6 |   6  0 | 20  *  *  as non-regular compound of 2{3}
      . β5o   ♦  5 |   0  5 |  * 12  *
sefa( β3β5o ) |  3 |   2  1 |  *  * 60

starting figure: x3x5o