Scull and bone on back of grave stone?

[AJH - Holmes and Gordon]

I came across this grave stone walking through my local grave yard. There is no link to my tree, I just find it intriguing. There is a skull and bone carved into the back of the head stone, which I thought was very strange. What is the reason they would do that?

From what I can make out, it reads ...

Barbara
Daughter of
Thomas Softley
Died may 5 173?
Al?o I?a be? his
Dangter died
??

At first I thought it read Danger at the bottom, and coupled with the skull on the back, I thought it very strange, but could it be mispelled daughter? Could it read 'also Ilabel his daughter', with 's' looking like 'f'. I didn't want to disturb below to read more.

The stone next to it is much more elaborate, and if for Thomas Softey who died 1761. Possibly the father, so Barbara could have died young?

The more I look at it, the more I want to know more! What do you think?

[AJH - Holmes and Gordon]

Apologies for the photos, trying to get them under 400kb each!

[AJH - Holmes and Gordon]

Last photo of both grave stones. Three photos in total (couldn't attach in a single post).

[Rhododendron]

Sculls on gravestones are a reminder of our mortality.  Sometimes they are found with crossbones or some other symbols. 

[Rhododendron]

And yes.  It is "Isabel his daughter..."

[Skoosh]

Common in old Scottish kirkyards, sometimes with "Memento Mori!" added.

Skoosh.

[Ruskie]

https://headstonesymbols.co.uk/?doing_wp_cron=1586866632.6712141036987304687500

[AJH - Holmes and Gordon]

Thanks for your replies. The last link was an interesting read, I walk through the graveyard every day to walk the dog, and look at the surnames out of interest but never really paid much attention to other details.