Solution

    PROGRAM Onion_Layers
     IMPLICIT NONE
     INTEGER :: n, layer, i, size_seed
      PRINT*, "Type in a seed for the Random Number Jenny"
      READ*, n
      CALL RANDOM_SEED(SIZE=size_seed)
      CALL RANDOM_SEED(PUT=(/(n, i = 1,size_seed)/))
      layer = depth()
      IF(layer .GT. 0)THEN
       WRITE(*,*) ' Bug found at depth ', layer
      ELSE
       WRITE(*,*) ' Bug not found'
      ENDIF

    CONTAINS

     RECURSIVE FUNCTION depth() RESULT(layer)
      INTEGER :: layer
      REAL    :: harvest
      INTEGER :: count = 0
       count = count + 1
       CALL RANDOM_NUMBER(harvest)
       WRITE(*,*) 'Random number = ' ,harvest
       IF(harvest .LT. .1)THEN
        layer = count
        RETURN
       ELSE
        layer = depth()
       ENDIF
      END FUNCTION depth
    END Program