I’ve not really got anywhere with this, except that it’s likely a crustacean I.e. shrimp type animal, (Thalassinoids) that lived in horizontal burrows in soft silty or sandy sediment. Their burrows can be maybe 5 cm across. However there are also worms that leave serpentine burrows like this (Thalassinoids), so that doesn’t really get us very far!
There are some amazing trace fossils – tracks- just over the border into Portugal, near Idanho, as well, and over Mojacar way to the east.
A lot of this area was shallow lakes and seas in the not too distant past (geologically) so loads of potential for traces!