PFILEs automatically in $ORACLE_HOME/dbs

In my Oracle 12.1.0.2 database (single-instance, but I also see this in a RAC system too) running on Oracle Linux 7, I see lots of files with cryptic file names. Here is a sample:

[oracle@myhost dbs]$ ls

07wKdh2k2x  8aTw7vvaEz  cknRhR6BNi  FOX3VCHxE7      JHGPXRyktk  nWzCyYBVvx    RRd4htHmn9         wSdYa5lLrU

0aHWoXnUDH  8jMVYlND00  cMsm2cZWFO  FrnnJd7XJD      JiTTEuViNX  nxxUf8Yt8F    rvCA1EoJfV         wsPT7VsB3r

0auGtmDz3E  8q0Gse3jJ2  cqxPTDXZRd  FX1SPeFeyS      JjrbpxVC3k  NYuJ6ogxQB    rXlWNJl1E1         WV5EpsHyi3

0kcnm7WjzG  8uS5BM2gOe  cu33EH4tr7  FxgCqkDkGT      JkScrQDOuz  o8RASbC9us    S1sB65Cjcn         wVKEKaVKCF

157vSqMTiq  8VlvllCfrX  CuHZJyvuCa  Fy7q6k4JIz      jmlAZH5Ili  OcoOY6FKvw    S3nxQuXQZU         x7wA2DRgCF