Pseudo-tail

The sharptail mola (Masturus lanceolatus) is a species of mola found circumglobally in tropical and temperate waters. It is similar in appearance to the ocean sunfish (Mola mola), but can be distinguished by the projection on its clavus (pseudo-tail). [Source: Wikipedia ]

Synonyms
Mucosa-lined hemiperineal anomaly
May Cause
Sacrococcygeal appendage
Mucosa-lined hemiperineal anomaly