Henley service fuse of some type. From the pics you can only surmise that the fire has melted the cut out it was in and the heat has probably made it fall out.
The fire investigators will be able to tell you more. But to start with I wouldn't touch anything until given full permission from any relevant authorities.
What is a Henley service fuse? Where is the main overload fuse?
This is an aftermath of a fuse board fire. I have attached pics of the burnt fuse boards/consumer units.
The EICR was done 12 months before and replaced the 1 plastic consumer units with a metal one, and the other consumer unit was metal already.
This was on the original report that they remedied:
1 4.2 Plastic DB C3-‘Improvement Recommended’
2 non ip rated bathroom light C2-‘Potentially Dangerous’
Urgent remedial action required
3 no grommet strip where cables entering a metal consumer unit C2-‘Potentially Dangerous’
Urgent remedial action required
4 bus bars to close together C2-‘Potentially Dangerous’
Urgent remedial action required
5 2.5 radial bunched in a 32amp ring C2-‘Potentially Dangerous’
Urgent remedial action required
Thanks to everyone who has replied