That’s probably an octopus or maybe a cuttlefish but not a squid.
Squid can’t be kept captive they die within a day or two. And only octopus have the flexibility to change into “a rock” and can be kept as pets.
But very slight chance its a cuttlefish because I can’t see very well if its completely changed shape or not in pic 2.
Source: I worked in a lab studying octopus and cuttlefish